Hawaii Ocean Time-series Program 
DATA REPORT 16 
2004 
October 2006 

Hawaii Ocean Time-series 
Data Report 16: 2004 


October 2006 

Lance A. Fujieki 
Fernando Santiago-Mandujano 
Paul Lethaby 
Cecelia Hannides 
Roger Lukas 
David Karl 


with contributions by: 
Robert Bidigare 
Matthew Church 
John Dore 
Michael Landry 
Ricardo Letelier 


University of Hawaii 
School of Ocean and Earth Science and Technology 
1000 Pope Road 
Honolulu, Hawaii 96822 

U.S.A. 

PREFACE 

Scientists working on the Hawaii Ocean Time-series (HOT) program have been making 
repeated observations of the hydrography, chemistry and biology of the water column at a station 
north of Oahu, Hawaii since October 1988. The objective of this research is to provide a 
comprehensive description of the ocean at a site representative of the North Pacific subtropical 
gyre. Cruises are made approximately once per month to the deep-water Station ALOHA (A 
Long-term Oligotrophic Habitat Assessment; 22. 45' N, 158. 00' W) located 100 km north of 
Oahu, Hawaii. Measurements of the thermohaline structure, water column chemistry, currents, 
optical properties, primary production, plankton community structure, and rates of particle 
export are made on each cruise. 

This document reports the data collected in 2004. However, we have included some data 
from 1988-2003 to place the 2004 measurements in the context of ongoing time-series 
observations. The data reported here are a subset of the complete data set. Summary plots are 
given for CTD, biogeochemical, optical, meteorological, navigational, thermosalinograph and 
ADCP observations. The complete data set resides on a pair of Sun workstations at the 
University of Hawaii. These data are in ASCII format, and can easily be accessed using either 
anonymous file transfer protocol (FTP) ,the World Wide Web (WWW) or the Hawaii Ocean 
Time-series Data Organization and Graphical System (HOT-DOGS). 

ACKNOWLEDGMENTS 

Many people participated in the 2004 cruises sponsored by the HOT program. Special 
thanks are due to Karin Bjrkman, Tara Clemente, Eric Grabowski, Thomas Gregory, Maya 
Iriondo imek, Dan Sadler and Blake Watkins for the tremendous amount of time and effort they 
have put into the program. Special thanks are given to Lisa Lum for her excellent administrative 
support of the program, Sharon DeCarlo for programming and data management, and Julia 
Hummon for ADCP processing. Tara Clemente and Eric Grabowski performed many of the core 
chemical analyses. Karin Bjrkman, Ken Doggett and Claire Mahaffey performed the nutrient 
analyses. Dan Sadler performed the carbon analyses. Daniel Fitzgerald and Maya Iriondo imek 
performed the salinity measurements. Matthew Markley and Melissa Fujimoto performed CTD 
processing. Xavier Murard collaborated in the production of a sampling procedures training 
video, and Alejandro Sanchez-Barba assisted in programming and data processing. Mark 
Valenciano, Brandon Shima and Kellie Terada provided additional technical support. We 
gratefully acknowledge the support from Nordeen Larson and Ken Lawson of Sea-Bird for 
helping us to maintain the quality of the CTD data throughout the HOT program. We also would 
like to thank the captains and crew of the R/V Kaimikai-o-Kanaloa, the R/V Kilo Moana, and 
the UH Marine Center staff for their efforts. Without the assistance of these and the many 
technicians, students and ancillary investigators, the data presented in this report could not have 
been collected, processed, analyzed and reported. Weather buoy data used in this report were 
obtained by the NOAA National Data Buoy Center (NDBC) and were provided to us by the 
National Oceanographic Data Center (NODC). We thank Pat Caldwell for his assistance. 

This data set was acquired with funding from the National Science Foundation (NSF) and 
State of Hawaii general funds. The specific grants which have supported our 2004 work are NSF 
grants OCE-0327513 (Lukas) and OCE-0326616 (Karl, Bidigare, Dore, Landry and Letelier). 

ii 


1.0 INTRODUCTION 
In response to the growing awareness of the oceans role in climate and global 
environmental change, and the need for additional and more comprehensive oceanic time-series 
measurements, the Board on Ocean Science and Policy (BOSP) of the National Research 
Council (NRC) sponsored a workshop on Global Observations and Understanding of the 
General Circulation of the Oceans in August 1983. The proceedings of this workshop (National 
Research Council 1984a) served as a prospectus for the development of the U.S. component of 
the World Ocean Circulation Experiment (WOCE). US-WOCE has the following objectives: 

 To understand the general circulation of the global ocean, to model with confidence its 
present state and predict its evolution in relation to long-term changes in the 
atmosphere. 
 To provide the scientific background for designing an observation system for long-
term measurement of the large-scale circulation of the ocean. 
In a parallel effort, a separate research program termed Global Ocean Flux Study (GOFS) 
focused on the oceans carbon cycle and associated air-sea fluxes of carbon dioxide. In 
September 1984, NRC-BOSP sponsored a workshop on Global Ocean Flux Study which 
served as an eventual blueprint for the GOFS program (National Research Council 1984b). In 
1986, the International Council of Scientific Unions (ICSU) established the International 
Geosphere-Biosphere Program: A Study of Global Change (IGBP), and the following year 
JGOFS (Joint GOFS) was designed as a Core Project of IGBP. US-JGOFS research efforts 
focus on the oceanic carbon cycle, its sensitivity to change and the regulation of the atmosphere-
ocean CO2 balance (Brewer et al., 1986). The broad objectives of US-JGOFS are: 

 To determine and understand on a global scale the time-varying fluxes of carbon and 
associated biogenic elements in the ocean. 
 To evaluate the related exchanges of these elements with the atmosphere, the sea floor 
and the continental boundaries (Scientific Committee on Oceanic Research 1990). 
In order to achieve these goals, four separate program elements were defined: (1) process 
studies to capture key regular events, (2) long-term time-series observations at strategic sites, (3) 
a global survey of relevant oceanic properties (e.g., CO2), and (4) a vigorous data interpretation 
and modeling effort to disseminate knowledge and to generate testable hypotheses. 

In 1987, two separate proposals were submitted to the US-WOCE and US-JGOFS 
program committees, respectively, by scientists at the University of Hawaii at Manoa, to 
establish a multi-disciplinary, deep water hydrostation in proximity to the Hawaiian islands. In 
July 1988, these proposals were funded by the National Science Foundation and Station 
ALOHA, the benchmark study site for the Hawaii Ocean Time-series program, was officially on 
the map (Karl and Lukas 1996). A sister station in the western North Atlantic Ocean, near the 
historical Panulirus Station, was likewise funded by the US-JGOFS program and is operated by 
scientists at the Bermuda Biological Station for Research, Inc. (Michaels and Knap 1996). 

The primary research objectives of these ocean measurement programs are to establish 
and maintain deep-water hydrostations for observing and interpreting physical and 

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biogeochemical variability. The program designs called for repeat measurements of a suite of 
core parameters at approximately monthly intervals, compilation of the data and rapid 
distribution to the scientific community. 

1.1 Hawaii Ocean Time-series Program 
The Hawaii Ocean Time-series (HOT) Program consists of several research components 
led by scientists at the University of Hawaii at Manoa (Table 1.1). The hydrographic (P.O.) and 
biogeochemistry & ecology (BEACH) components are fully integrated operationally and are 
both involved in all aspects of planning and execution of HOT Program objectives. 

Table 1.1: HOT Research Components in 2004 

Principal Investigators Project Title 
Robert R. Bidigare 
John E. Dore 
David M. Karl 
Michael R. Landry 
Ricardo M. Letelier 
Roger B. Lukas 
Phytoplankton community structure 
BEACH Carbon Component 
BEACH Core Component 
Zooplankton community structure 
Remote Sensing & Ocean Optics 
Physical Oceanography Component 

1.2 Scientific objectives for HOT 
The primary objective of HOT is to obtain a long time-series of physical and 
biogeochemical observations in the North Pacific subtropical gyre that will address the goals of 
the US Global Change Research Program. The objectives specific to the Physical Oceanography 
program are to: 

 Document and understand seasonal and interannual variability of water masses. 
 Relate water mass variations to gyre fluctuations. 
 Determine the need and methods for monitoring currents at Station ALOHA. 
 Develop a climatology of short-term physical variability. 
In addition to these general primary objectives, the physical oceanographic component of 
HOT provides CTD/rosette sampling support for the BEACH time-series sampling program, and 
supports development of new instrumentation for hydrographic observations. 

The objectives of HOT specific to the BEACH program are to: 

 Document and understand seasonal and interannual variability in the rates of primary 
production, new production and particle export from the surface ocean. 
 Determine the mechanisms and rates of nutrient input and recycling, especially for 
nitrogen (N) and phosphorus (P) in the upper 200 m of the water column. 
2



 Measure the time-varying concentrations of dissolved inorganic carbon (DIC) in the 
upper water column and estimate the annual air-to-sea CO2 flux. 
In addition to these primary objectives, the HOT Program provides logistical support for 
numerous complementary research programs (Table 1.2). A complete listing of these projects 
can be obtained from the HOT-BEACH web page (hahana.soest.hawaii.edu/hot/ancillary.html). 

Table 1.2: Ancillary Projects Supported by HOT in 2004 

Principal Investigator(s) Institution Agency Project Title 
John Bullister 
Penny ChisholmCharles Keeling 
Paul Quay 
PMEL 
MIT 
UCSD 
Scripps Inst. 
Oceanography 
Univ. Washington 
NSF 
NSF 
NSF 
NOAA 
CFC and SF6 geochemistry 
Prochlorococcus ecotype 
dynamics 
13C/12C ratio of atmosphere 
carbon dioxide and oceanic 
carbon in relation to the global 
carbon cycle13C/12C of dissolved inorganic 
carbon in the ocean 

1.3 HOT Study Site 
There are both scientific and logistical considerations involved with the establishment of 
any long-term, time-series program. Foremost among these are site selection, choice of variables 
and general sampling design and sampling frequency. Equally important are choices of 
analytical methods for a given candidate variable, an assessment of the desired accuracy and 
precision of each measurement, availability of suitable reference materials, the hierarchy of 
sampling replication and mesoscale horizontal variability. 

We evaluated several major criteria prior to selection of the site for the HOT oligotrophic 
ocean benchmark hydrostation. First, the station must be located in deep water (>4000 m), 
upwind (north-northeast) of the main Hawaiian Islands and of sufficient distance from land to be 
free from coastal ocean dynamics and biogeochemical influences. On the other hand, the station 
should be close enough to the port of Honolulu to make relatively short duration (<5 d) monthly 
cruises logistically and financially feasible. A desirable, but less stringent criterion would locate 
the station at, or near, previously studied regions of the central North Pacific Ocean, in particular 
Station GOLLUM. Documentation of oceanic time-series measurements in the North Pacific 
Ocean can be found in Karl and Winn (1991), Karl et al. (1996b), Karl and Lukas (1996) and in 
the HOT-BEACH web page (hahana.soest.hawaii.edu/hot/hot_jgofs). 

3



24oN 

23oN 

22oN 

21oN 

20oN 

19oN 

18oN 
163oW 162oW 161oW 160oW 159oW 158oW 157oW 156oW 155oW 154oW 

-4000 
-4000 
-4000 
-4000 
-4000 
-4000 
-4000 
-4000 
-4000 
-4000 
-2000 
-2000 
-2000 
-2000 
HAWAIIAN ISLANDS 
Kauai 
Oahu 
Maui 
Hawaii 
1 (Kahe) 
2 (ALOHA) 
6 (Kaena) 
NDBC #51001 
Sediment Trap X 
0 50 100 
nmi 
Figure 1.1: Map of the Hawaiian Islands showing the locations of the HOT stations occupied in 
2004 and the NOAA-NDBC weather buoy #51001. Depth contours are in meters. 

After consideration of these criteria, we established our primary sampling site at 22 45' 
N, 158 W at a location approximately 100 km north of the island of Oahu (Figure 1.1), and 
generally restrict our monthly sampling activities to a circle with an 10 km radius around this 
nominal site (Figure 1.2). Station ALOHA is in deep water (4750 m) and is more than one 
Rossby radius (50 km) away from steep topography associated with the Hawaiian Ridge. We 
also established a coastal station WSW of the island of Oahu, approximately 10 km off Kahe 
Point (21 20.6' N, 158 16.4' W) in 1500 m of water. Station Kahe serves as a coastal analogue 
to our deep-water site and the data collected there provide a near-shore time-series for 
comparison to our primary open ocean site. Station Kahe is also used to test our equipment each 
month before departing for Station ALOHA, and to orient new personnel at the beginning of 
each cruise. From January 1997 to October 2000, a physical-biogeochemical mooring was 
deployed to obtain continuous measurements of various atmospheric and oceanographic 
parameters. The mooring was located at 22 28' N, 158 8' W and was designated as Station 
HALE-ALOHA. 

In August 2004, HALE-ALOHA was redeployed at a site 6 nautical miles west of Station 
ALOHA (22 46' N, 158 5.5' W) as part of the Multi-diciplinary Ocean Sensors for 
Environmental Analyses and Networks (MOSEAN) project. MOSEAN is directed toward new 
technologies that will lead to increased observations that are essential for solving a variety of 

4



interdisciplinary oceanographic problems. These include: biogeochemical cycling, climate 
change effects, ocean pollution, harmful algal blooms (HABs), ocean ecology and underwater 
visibility. This site, also called Station 51, is a collaboration with the University of California 
Santa Barbara and WET Labs. 

Also in August 2004, a surface mooring outfitted for meteorological and oceanographic 
measurements was deployed 6 nautical miles east of Station ALOHA (22 46' N, 157 54' W). 
Ever since, CTD casts have been taken during various HOT cruises near the mooring for 
calibration of the moored instruments. This site, named WHOTS is a collaboration with the 
Woods Hole Oceanographic Institution. It has also been called Station 50. It is intended to 
provide long-term, high-quality air-sea fluxes as a coordinated part of the HOT program and 
contribute to the goals of observing heat, fresh water and chemical fluxes. The approach is to 
maintain a surface mooring by successive mooring turnarounds (Plueddemann, et al., 2006). 
These observations will be used to investigate air sea interaction processes related to climate 
variability. 

Locations and dates of occupancy of HOT water column and bottom recording stations 
are available on the HOT-BEACH web page (hahana.soest.hawaii.edu/hot/locations.html). 

1.4 Field Sampling Strategy 
HOT program cruises are conducted at approximately monthly intervals; the exact timing 
is dictated by the availability of research vessels. From HOT-1 (October 1988) to HOT-65 
(August 1995), with the exception of HOT-42 and HOT-43 (November and December 1992), 
each cruise was 5 d in duration (port to port). Beginning with HOT-66 (September 1995) the 
standard HOT cruise was reduced to 4 d in order to accommodate the additional mooring-based 
HOT field programs within a fixed per annum allocation of ship days. 

From HOT-1 (October 1988) to HOT-32 (December 1991), underway expendable 
bathythermograph (XBT; Sippican T-7 probes) surveys were conducted at 13 km spacing on the 
outbound transect from Station Kahe to Station ALOHA. These surveys were later discontinued 
because the space-time correlation of the energetic, internal semi-diurnal tides made it difficult 
to interpret these data. From February 1995 until December 1997 we added an instrumented, 1.5 
m Endeco towfish package (Sea-Bird CTD, optical plankton counter and fluorometer) to our 
sampling program (Tupas et al., 1997). Upper water column currents are measured both 
underway and on station using a hull-mounted Acoustic Doppler Current Profiler (ADCP), when 
available (Firing, 1996). 

Underway near-surface measurement of a variety of physical, chemical and biological 
properties were made possible by sampling seawater through a pumped intake system positioned 
in the hull of the R/V Moana Wave. In May 1995, a thermosalinograph was installed in line to 
the ship's seawater intake system. In July 1996, the existing system was replaced with a non-
contaminating PVC/stainless steel system. A flow-through fluorometer was installed in 1996. 
The R/V Ka'imikai-o-Kanaloa is outfitted with a similar seawater intake system to which the 
existing instruments were installed when R/V Moana Wave was retired. The R/V Kilo Moana 
also has a similar system which was sampled from during 2004. 

5



 The majority of our sampling effort, approximately 60-72 h per standard HOT cruise, is 
spent at Station ALOHA. High vertical resolution environmental data are collected with a Sea-
Bird CTD having external temperature (T), conductivity (C), dissolved oxygen (DO) and 
fluorescence (F) sensors and an internal pressure (P) sensor. A Sea-Bird 24-place carousel and 
an aluminum rosette that is capable of supporting 24 12-L PVC bottles are used to obtain water 
samples from desired depths. The CTD and rosette are deployed on a 3-conductor cable allowing 
for real-time display of data and for tripping the bottles at specific depths of interest. The CTD 
system takes 24 samples s-1 and the raw data are stored both on the computer and, for 
redundancy, on VHS-format video tapes. 

Up until HOT-96 (August 1998), we routinely conducted a dedicated hydrocast to collect 
clean water samples for biological rate measurements, using General Oceanics Go-Flo bottles, 
Kevlar line, a metal-free sheave, Teflon messengers and a stainless steel bottom weight. During 
HOT-97 through HOT-118, due to the frequency of mis-trips & the inability to know the exact 
depth from which samples were collected, replicate samples were taken from the CTD rosette 
and the Go-Flo bottles. Comparisons with the Go-Flo collected samples showed there was no 
statistical difference in rates of 14C-primary production derived from samples collected using the 
Go-Flo bottles or the CTD rosette. As a result, beginning with HOT-119 (October 2000), we 
have collected samples for biological rate measurements only from the rosette. 

A free-drifting sediment trap array, identical in design to the VERTEX particle 
interceptor trap (PIT) array (Knauer et al., 1979), is deployed at Station ALOHA for an 
approximately 60 h period to collect sinking particles for chemical and microbiological analyses. 

Sampling at Station ALOHA typically begins with sediment trap deployment followed by 
a deep (> 4700 m) CTD cast and a burst series of at least 13 consecutive 1000 m casts, on 3-h 
intervals, to span the local inertial period (~ 31 h) and three semidiurnal tidal cycles. The drift 
tracks of the sediment trap arrays and the location of the CTD casts for each cruise are shown in 
Figure 1.2. The repeated CTD casts enable us to calculate an average density profile from which 
variability on tidal and near-inertial time scales has been removed. These average density 
profiles are useful for the comparison of dynamic height and for the comparison of the depth 
distribution of chemical parameters from different casts and at monthly intervals. This sampling 
strategy is designed to assess variability on time scales of a few hours to a few years. Very high 
frequency variability (< 6 h) and variability on time scales of between 3-60 d are not adequately 
sampled with our ship-based operations. 

Water samples for a variety of chemical and biological measurements are routinely 
collected from the surface to within 10 m of the seafloor. To the extent possible, we collect 
samples for complementary biogeochemical measurements from the same or from contiguous 
casts to minimize aliasing caused by time-dependent changes in the density field. This approach 
is especially important for samples collected in the upper 350 m of the water column. 
Furthermore, we attempt to sample from common depths and specific density horizons each 
month to facilitate comparisons between cruises. Water samples for salinity determinations are 
collected from every water bottle to identify sampling errors. Approximately 20% of the water 
samples are collected and analyzed in duplicate or triplicate to assess and track our precision in 
sample analyses. 

6



The HOT program was initially conceived as being a deep ocean, ship and mooring based 
observation experiment that would have an approximately 20 y lifetime. Consequently, we 
selected a core suite of environmental variables that might be expected to display detectable 
change on time scales of several days to one decade. Except for the availability of existing 
satellite and ocean buoy sea surface data, the initial phase of the HOT program (Oct 1988 - Feb 
1991) was entirely supported by research vessels. In February 1991, an array of five inverted 
echo sounders (IES) was deployed in an approximately 150 km2 network around Station 
ALOHA (Chiswell 1996) and in June 1992, a sequencing sediment trap mooring was deployed a 
few km north of Station ALOHA (Karl et al., 1996a). In 1993, the IES network was replaced 
with two strategically-positioned instruments: one at Station ALOHA and the other at Station 
Kaena. The IES at Station Kaena was retired in October 1995. Between 1994 and 1999, a single 
IES was positioned and annually replaced at Station ALOHA. 

7



HOT-155 

Drift Casts 

158 20 158 00 157 40 158 20 
22 20 
22 40 
23 00 
s 
Latitude (N) 
22 50 

1 
235679101415 
13 
4 1112 
8 

Latitude (N) Latitude (N)

22 45 

22 40 

158 10 158 05 158 00 158 55 157 50 
Longitude (W) Longitude (W) 

HOT-156 

Drift Casts 

13 
12 
11 
124356 78 101415 
9


Latitude (N) 

23 00 

22 50 

s 
22 45 

22 40 

22 40 
22 20 
158 20 158 00 157 40 
Longitude (W) 
158 20 158 10 158 05 158 00 158 55 
Longitude (W) 
157 50 

Figure 1.2: [Left panels] Drift tracks of the sediment trap array during each HOT cruise in 2004. 
Starting point of deployment indicated by S. [Right panels] CTD cast locations during each 
HOT cruise in 2004. Location numbers correspond to cast numbers. Dashed line indicates the 
10 km radius circle defining the station. 

8



HOT-157 

Drift Casts 

22 50 

22 20 
22 40 
23 00 
Latitude (N)
s 
Latitude (N)
123468971011 
12 
5 
13 

22 45 

22 40 

158 20 158 00 157 40 158 20 158 10 158 05 158 00 158 55 157 50 
Longitude (W) Longitude (W) 

HOT-158 

Drift Casts 

22 50 

158 20 158 00 157 40 158 20 
22 20 
22 40 
23 00 
Longitude (W) 
s 
Latitude (N)
13 
14 
2 134 
6587 
12 
15 
16 
9 
1011

22 45 

22 40 

158 10 158 05 158 00 158 55 157 50 
Longitude (W) 

Latitude (N) 

Figure 1.2: continued 

9



HOT-159 

Drift Casts 

22 50 

22 20 
22 40 
23 00 
Latitude (N)
s 
Latitude (N)
1 
29155461011 12 1314 
783

22 45 

22 40 

158 20 158 00 157 40 158 20 158 10 158 05 158 00 158 55 157 50 
Longitude (W) Longitude (W) 

HOT-160 

Drift Casts 

22 50 

158 20 158 00 157 40 158 20 
22 20 
22 40 
23 00 
Longitude (W) 
s 
Latitude (N)
1345796810151617 
1314 
11 
12 2 

22 45 

22 40 

158 10 158 05 158 00 158 55 157 50 
Longitude (W) 

Latitude (N) 

Figure 1.2: continued 

10



HOT-161 

Drift Casts 

22 20 
22 40 
23 00 
Latitude (N) 
22 40 
22 45 
22 50 
Latitude (N)
12345
158 20 158 00 157 40 158 20 158 10 158 05 158 00 158 55 157 50 
Longitude (W) Longitude (W) 

HOT-162 

Drift Casts 

22 50 

158 20 158 00 157 40 158 20 
22 20 
22 40 
23 00 
Longitude (W) 
s 
Latitude (N)
12 354769 812 
10 
11

Latitude (N)

22 45 

22 40 

158 10 158 05 158 00 158 55 157 50 
Longitude (W) 

Figure 1.2 continued: Due to the failure of the ships port generator during HOT-161, the cruise 
had to be cut short. No sediment trap data is available for this cruise. 

11



HOT-163 

Drift Casts 

22 50 

22 20 
22 40 
23 00 
Latitude (N)
s 
Latitude (N)
14 1213 
2 11 10 
154639151687

22 45 

22 40 

158 20 158 00 157 40 158 20 158 10 158 05 158 00 158 55 157 50 
Longitude (W) Longitude (W) 

HOT-164 

Drift Casts 

22 50 

158 20 158 00 157 40 158 20 
22 20 
22 40 
23 00 
Longitude (W) 
s 
Latitude (N)
182764531415 
9 1011 
12 
13 

22 45 

22 40 

158 10 158 05 158 00 158 55 157 50 
Longitude (W) 

Latitude (N) 

Figure 1.2: continued 

12



HOT-165 

Drift Casts 

22 50 

22 20 
22 40 
23 00 
Latitude (N)
s 
Latitude (N)
10 123 465789 
11 
1214 
1516 
13 

22 45 

22 40 

158 20 158 00 157 40 158 20 158 10 158 05 158 00 158 55 157 50 
Longitude (W) Longitude (W) 

HOT-166 

Drift Casts 

22 50 

158 20 158 00 157 40 158 20 
22 20 
22 40 
23 00 
Longitude (W) 
s 
Latitude (N)
47651681 
2 
3 
9 
1011 
121314 
15 
17

22 45 

22 40 

158 10 158 05 158 00 158 55 157 50 
Longitude (W) 

Latitude (N) 

Figure 1.2: continued 

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1.5 Core Measurements, Experiments and Protocols 
The suite of core measurements provides a database to validate and improve existing 
biogeochemical models. Our list of core measurements has evolved since the inception of the 
HOT program in 1988, and now includes both continuous and discrete physical, biological and 
chemical ship-based measurements, optical, in situ biological rate experiments, and observations 
and sample collections from bottom-moored instruments and buoys (Table 1.3). Continuity in 
the measurement parameters and their quality, rather than continuity in the methods employed, is 
of greatest interest. Detailed analytical methods are expected to change over time through 
technical improvements. In addition to the core data, specialized measurements and process-
oriented experiments have also been conducted at Station ALOHA (Table 1.3). 

Table 1.3: Parameters Measured at Station ALOHA during 2004 

Parameter Depth Range (m) Analytical Procedure 
I. Continuous Measurements 
Depth (Pressure) 0-4750 Pressure transducer on Sea-Bird CTD 
package 
Temperature 0-4750 Thermistor on Sea-Bird CTD package 
Conductivity (Salinity) 0-4750 Conductivity sensor on Sea-Bird CTD 
package, standardization with Guildline 
AutoSal using Wormley seawater 
standard 
Dissolved Oxygen 0-4750 Sea-Bird sensor on Sea-Bird CTD 
package with Winkler standardization 
Fluorescence (Chloropigment) 0-4750 Sea-Point chlorophyll fluorometer on 
Sea-Bird CTD package with discrete 
chlorophyll calibration 

II. Water Column Chemical Measurements 
Oxygen 0-4750 Winkler titration 
Dissolved Inorganic Carbon 0-4750 Coulometry 
Total Alkalinity 0-4750 Automated Gran titration 
pH 0-4750 Spectrophotometric 
Nitrate Plus Nitrite 0-4750 Autoanalyzer 
Soluble Reactive Phosphorus 
(SRP) 
0-4750 Autoanalyzer 
Silicate 0-4750 Autoanalyzer 
Low Level Nitrate Plus Nitrite 0-200 Chemiluminescence 
Low Level SRP 0-200 Magnesium-induced coprecipitation 
Dissolved Organic Carbon 0-4750 High temperature catalytic oxidation 
Dissolved Organic Nitrogen 0-1000 UV oxidation of total nitrogen 
Dissolved Organic Phosphorus 0-1000 UV oxidation of total phosphorus 
Particulate Carbon 0-350 Mass Spectrometry 

14



Particulate Nitrogen 0-350 Mass Spectrometry 
Particulate Phosphorus 0-350 High temperature combustion 
Particulate Silica 0-175 Base Hydrolysis with Amonium 
Molybdate Colorimetry 

III. Biomass Measurements 
Chlorophyll a and Pheopigments 0-175 Fluorometric analysis using 10-AU 
Chlorophyll a, b and c 0-175 Fluorometric analysis using TD-700 
Pigments 0-175 High Performance Liquid 
Chromatography (HPLC) 
Phycoerythrin 0-175 Fluorometric analysis using TD-700 
Adenosine 5'-triphosphate 0-350 Firefly bioluminescence 
Bacteria and Cyanobacteria 0-175 Flow cytometry 
Mesozooplankton 0-175 Net tows, elemental analysis 

IV. Carbon Assimilation and Particle Flux 
Primary Production 0-125 Clean 14C incubations 
Carbon, Nitrogen, Phosphorus , 
Silica 
150 Free-floating particle interceptor traps 
V. Currents 
Acoustic Doppler Current Profiler 10-300 Hull mounted, RDI #VM-150 
VI. Bow Intake System 
Temperature 3 Sea-Bird remote temperature sensor 
Conductivity (Salinity) 3 Sea-Bird temperature and conductivity 
sensors inside the thermosalinograph 
package 
Fluorometry (Chloropigment) 3 Fluorometric analysis using 10-AU 

VII. Optical Measurements 
Incident Irradiance Surface LI-COR LI-1000 and Biospherical 
collector 
Surface Downwelling Irradiance Surface Biospherical Surface Reference Sensor 
PRR-610 
Upwelling Radiance and 
Downwelling Irradiance 
0-175 Biospherical Profiling Reflectance 
Radiometer PRR-600 
Absorption and Beam Attenuation 0-250 WET Labs AC-9 connected to Sea-Bird 
CTD package 
Fast Repetition Rate Fluorometry 0-250 Chelsea FASTtracka Dynamic 
Photosynthetic Fluorometer 

VIII. Moored Instruments 
Sequencing Sediment Traps 2800, 4000 Parflux MK7-21 
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These selected measurements are part of a much larger HOT program data set on 
physical and biogeochemical variability at Station ALOHA that has been collected since October 
1988. The complete data set is available to the community by several methods that are described 
in Section 8.0 of this report. 

This report presents selected core data collected during the 16th full year of the HOT 
Program (January-December 2004). During this period, twelve regular HOT cruises were 
conducted using the University of Hawaii research vessels R/V Ka'imikai-o-Kanaloa (KOK) and 
R/V Kilo Moana (Table 1.4). University of Hawaii shipboard technical assistance personnel 
assisted a total field scientific crew of 61 HOT staff, students and visiting scientists (Table 1.5) 
in our 2004 field work. 

Table 1.4: Chronology of 2004 HOT Cruises 

Cruise Ship Depart Return 
155 R/V KOK 20 January 2004 24 January 2004 
156 R/V KOK 23 February 2004 27 February 2004 
157 R/V Kilo Moana 18 March 2004 22 March 2004 
158 R/V KOK 19 April 2004 23 April 2004 
159 R/V KOK 17 May 2004 21 May 2004 
160 R/V KOK 14 June 2004 18 June 2004 
161 R/V KOK 12 July 2004 14 July 2004 
162 R/V KOK 14 August 2004 18 August 2004 
163 R/V KOK 27 September 2004 1 October 2004 
164 R/V KOK 29 October 2004 2 November 2004 
165 R/V KOK 26 November 2004 30 November 2004 
166 R/V KOK 18 December 2004 23 December 2004 

Table 1.5: 2004 Cruise Personnel (shaded area = cruise participant) 

Cruise Participants 
155156157158159160161162163164165166 
Andrioni, Santiago 
Becker, Jamie 
Berini, Carole 
Bjrkman, Karin 
Brum, Jennifer 
Bullister, John 
Chapman, Kai 
Church, Matt 
Clemente, Tara 
Daniels, Marissa 
Kinnear 

16



Cruise Participants 
155156157158159160161162163164165166 
Dafner, Evgeny 
Deschenes, Bryan 
Devol, Allan 
Donachie, Stuart 
Emerson, Steve 
Fitzgerald, Daniel 
Foster, Rachel 
Fujieki, Lance 
Giles, Katie 
Grabowski, Eric 
Grabowski, Marcie 
Gregory, Thomas 
Hayagawa, Darrin 
Howe, Bruce 
Iriondo, Maya 
Jachowski, Nick 
Kemp, John 
LaRue, Kelly 
Lethaby, Paul 
Lukas, Roger 
Mahdi, Leena 
McAndrew, Patricia 
Miller, Darius 
Miller, Misty 
Murard, Xavier 
Murphy, David 
Nakagawa, Kazuhiro 
Nichols, David 
Nicholson, David 
Park, Bora 
Peery, Tristan 
Pequignet, Christine 
Rappe, Michael 
Rii, Shimi 
Rivera, Andrea 
Rosbrugh, Damion 
Sadler, Daniel 
Santiago-Mandujano, 
Fenando 
Sanchez, Alejandro 
Schwerin-Whyte, 
Rebecca 
Shephard-Jones, Blade 

17



Cruise Participants 
155156157158159160161162163164165166 
Sheridan, Cecelia 
Simmons, Melinda 
Snyder, Jefrey 
Spada, Frank 
Stone, David 
Tognacchini, Camilla 
Valenciano, Mark 
Van Mooy, Benjamin 
Watkins, Blake 
Wells, Carolyn 

18



2.0 SAMPLING PROCEDURES AND ANALYTICAL METHODS 
A comprehensive summary of all sampling and analytical methods currently used in the 
HOT program along with information on measurement accuracy and precision can be found in 
the "Hawaii Ocean Time-series Program Field and Laboratory Protocols" manual. Brief 
summaries of methods as well as calibration specifications and quality control / quality 
assurance information for 2004 are presented in this report. Hydrographic sampling methods are 
included in "WOCE Hydrographic Sampling Procedure. A primer for ship-board operations at 
the Hawaii Ocean Time-series Station". 

2.1 CTD Profiling 
Continuous measurements of temperature, salinity, oxygen and fluorescence are made 
with a Sea-Bird SBE-9/11Plus CTD package with dual temperature, salinity and oxygen sensors 
and fluorometer described in Tupas et al. (1995). CTD underwater unit #91361 was used during 
HOT-155 through 160. CTD #92859 was used during HOT-161 through 166. 

CTD casts are made at Stations Kahe and ALOHA during each cruise. A CTD cast to 
1000 m is made at Station Kahe. This station was not visited during HOT-166. 

At Station ALOHA, a burst of consecutive CTD casts to 1000 m is made over 36 hours to 
span the local inertial period and three semi-diurnal tidal cycles. One WOCE standard cast 
within 10 m of the bottom is made during each cruise. A second deep cast was obtained at this 
Station during all the 2004 cruises except HOT-157 and 161. 

A CTD cast to 2400 m was conducted at Station Kaena during every 2004 cruise except 
HOT-157, 161, and 162. 

CTD casts have been conducted during cruises near the WHOTS mooring (Station 50), 
and near the MOSEAN mooring (Station 51) since August 2004, for calibration of the moorings' 
sensors. Casts to 200-m were conducted at these two stations during cruises HOT-162 through 
166, except that station 51 was not occupied during HOT-165, and station 50 was not occupied 
during HOT-166. 

2.1.1 Data Acquisition and Processing 
CTD data were acquired at a rate of 24 samples per second. Digital data were stored on a 
laptop personal computer and, for redundancy, the analog signal was recorded on VHS 
videotapes. Backups of CTD data were made onto Zip disks and later onto compact disks. The 
raw CTD data were quality controlled and screened for spikes as described in Winn et al. (1993). 
Data alignment, averaging, correction and reporting were done as described in Tupas et al. 
(1993). Salinity spike rejection parameters were modified for some cruises in 2004 because of 
rough sea conditions. Spikes occur when the CTD samples the disturbed water of its wake; 
therefore, samples from the downcast are rejected when the CTD is moving upward or when its 
acceleration exceeds 0.5 m s-2 in magnitude. Cruises 155, 156, and 157 were conducted under 

19



relatively rough conditions. The CTD acceleration cutoff value had to be increased to between 

0.55 and 0.65 m s-2 for some of the casts to relax the data rejection criteria and avoid eliminating 
an excessive number of points. 
The data were additionally screened by comparing the temperature and conductivity 
sensor pairs. These differences permitted identification of problems in the sensors. Only the data 
from one set of T-C sensors and one oxygen sensor, whichever was deemed most reliable, is 
reported here. 

Temperature is reported in the ITS-90 scale. Salinity and all derived units were calculated 
using the UNESCO (1981) routines; salinity is reported in the practical salinity scale (PSS-78). 
Oxygen is reported in mol kg-1 and Chloropigment (Fluorescence) in g/l. 

2.1.2 Sensor Corrections and Calibrations 
2.1.2.1 Pressure 
The pressure calibration strategy employed a high-quality quartz pressure transducer as a 
transfer standard. Periodic recalibrations of this lab standard were performed with a primary 
pressure standard. The transfer standard was used to check the CTD pressure transducers. The 
corrections applied to the CTD pressures included a constant offset determined at the time that 
the CTD first enters the water on each cast, and a pressure dependent offset, obtained from semiannual 
bench tests between the CTD sensor and the transfer standard. 

2.1.2.1.1 Transfer Standard Calibration 
The transfer standard is a Paroscientific Model 760 pressure gauge equipped with a 
10,000-PSI transducer. This instrument was purchased in March 1988, and was originally 
calibrated against a primary standard. Subsequent recalibrations have been performed every 2.5 
years on average either at the Northwest Regional Calibration Center or at the Scripps Institute 
of Oceanography. The latest calibrations were conducted at the Scripps Institute of 
Oceanography in April 1999, May 2001, and May 2003. 

2.1.2.1.2 CTD Pressure Transducer Bench Tests 
CTD pressure transducer bench tests were done using an Ametek T-100 pump and a 
manifold to apply pressure simultaneously to the CTD pressure transducer and to the transfer 
standard. All these tests had points at six pressure levels between 0 and 4500 dbar, increasing 
and decreasing pressures. 

The results of bench tests for sensors #75434 (primary CTD #91361), and #51412 
(backup CTD #92859) are shown in Table 2.1. Tests before September 1998 do not include the 
0-dbar offset because problems in the experimental settings during those tests deemed those data 
unreliable. 

20



Pressure transducer #75434 was used during cruises HOT-155 through 160. Pressure 
transducer #51412 was used during HOT-161 through 166. A 1.14 dbar correction was applied 
to the pressure offset at 0 dbar during data collection for casts conducted with sensor #51412 
(however, a more accurate offset was later determined for the time that the CTD first enters the 
water on each cast). On-deck CTD pressures are regularly recorded during cruises at the 
beginning and at the end of each CTD cast, the mean of these pressures throughout each cruise is 
plotted in Figure 2.1 (the 1.14 dbar offset correction applied to casts with sensor #51412 has 
been removed in this plot for comparison with previous data). The before-cast pressures for both 
sensors are about 0.3 dbar higher than the 0 dbar offset from the 2004 calibrations (Table 2.1). 
The cause of this difference is because prior to the pressure tests, the CTD is powered on 24 
hours for full stabilization; while the on-deck pressures are recorded only about 10 min after the 
CTD is powered on. Pressure stabilization tests conducted in our lab have indicate that our CTD 
pressure sensors show a decrease of about 0.8 dbar during the first 10 minutes after applying 
power to the CTD, and the pressure continues to drop a few tenths of a decibar until reaching full 
stabilization a few hours later. 

The mean difference between before-cast and an after-cast on-deck pressure is about 0.5 
dbar (Figure 2.1), larger than the hysteresis measured during the bench tests. This on-deck 
"hysteresis" is actually a residual temperature sensitivity effect of the pressure sensor caused 
when the CTD is submerged in cold water during casts, which has typical values of the order of 

0.5 dbar (Nordeen Larson, personal communication, 1999). Our bench tests do not show this 
effect because they are conducted at constant room temperature. 
The 0-4500 dbar pressure offset and hysteresis from the bench tests have been within 
expected values and nearly constant for the two sensors. The 0-4500 pressure offset for sensor 
#51412 suffered a slight increase during 2004-2005. A linear pressure dependent offset is 
applied during data collection for sensor #51412, to correct for the 0-4500 dbar offset. 

Table 2.1: CTD Pressure Calibrations against transfer standard. Offset at 0 dbar for tests before 
September 1998 are not shown (see text). Units are decibars. 

Calibration Date Offset @ 0 dbar 0-4500 dbar offset Hysteresis 
Sea-Bird SBE-911 Plus #91361 / Pressure Transducer #75434 
17 February 2005 0.1 0.4 0.08 
3 July 2004 0.49 0.17 0.05 
9 February 2004 0.44 0.20 0.12 
28 July 2003 0.45 0.12 0.15 
5 February 2003 0.39 0.05 0.15 
16 July 2002 0.43 0.15 0.1 
28 January 2002 0.35 0.23 0.1 
1 August 2001 0.1 -0.10 0.1 
6 February 2001 0.24 -0.02 0.1 
15 August 2000 0.18 0.12 0.1 
13 January 2000 0.1 0.13 0.08 
24 June 1999 -0.03 0.20 0.1 
Sea-Bird SBE-911 Plus #92859 / Pressure Transducer #51412 

21



16 February 2005 1.35 0.75 0.15 
4 July 2004 1.16 0.64 0.15 
10 February 2004 1.28 0.53 0.1 
29 July 2003 1.25 0.55 0.1 
5 February 2003 1.15 0.55 0.1 
17 July 2002 1.2 0.5 0.1 
31 January 2002 1.2 0.5 0.2 
29 June 2001 1.14 0.5 0.1 
5 February 2001 1.1 0.56 0.03 

16 August 2000 1.05 0.6 0.05 
14 January 2000 1.1 0.55 0.05 
25 June 1999 1.0 0.47 0.05 
26 January 1999 0.95 0.55 0.05 
14 September 1998 1.25 0.55 0.05 
12 June 1997 0.65 0.05 
31 January 1997 0.5 0.08 
30 August 1996 0.45 0.01 
5 December 1995 0.65 0.07 
21 August 1995 0.45 0.05 
16 December 1994 0.45 0.05 

22



Sensor SN 75434. Median on-deck pressure per cruise, before (o) and after (x) cast 

J FMAMJ J ASOND 
2004 

Sensor SN 51412. Median on-deck pressure per cruise, before (o) and after (x) cast

J FMAMJ J ASOND 
2004 

-0.2 
-0.1 
0.0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1.0 
Cruise .160159158157156155 
Pressure (dbar) 
0.80 
0.90 
1.00 
1.10 
1.20 
1.30 
1.40 
1.50 
0.80 
0.90 
1.00 
1.10 
1.20 
1.30 
1.40 
1.50Cruise .166165164163162161 
Figure 2.1: Median value of on-deck pressure measured with the CTD pressure sensors #75434 
and #51412, before (circles) and after (crosses) each cast for HOT cruises 155-166. Error bars 
are one standard deviation from the mean. Cruise numbers are shown below the upper X-axis. 

23



2.1.2.2 Temperature 
Given the demonstrated stability of our Sea-Bird SBE-3-Plus temperature transducers, 
we decided to reduce the frequency of calibrations from near-monthly to about every two 
months. Two temperature transducers #2700, and #2454 were used in 2004 and were calibrated 
at Sea-Bird after cruises HOT-155, 157, 160, 162, 164, and 166. SBE-3-Plus transducer #2242 
and SBE-3-02/F transducer #1416 were backup sensors and were also calibrated together with 
sensors #2700, and #2454. The history of the sensors, as well as the procedures followed to 
obtain the sensor drift from the Sea-Bird calibrations are well-documented in Santiago-
Mandujano et al. (2002, 2001, 1999), Tupas et al. (1993, 1994a, 1995, 1997, 1998) and Karl et 
al. (1996). Calibration coefficients obtained at Sea-Bird for these sensors after 2003 and used in 
the drift estimates are presented in Table 2.2. These coefficients were used in the following 
formula that gives the temperature (in C) as a function of the frequency signal (f): 

temperature = 1/{a+b[ln(f0/f)]+c[ln2(f0/f)]+d[ln3(f0/f)]}-273.15 (1) 

Table 2.2: Calibration coefficients for Sea-Bird temperature sensors. RMS residuals from 
calibration give an indication of quality of the calibration. Sensors #2045, #1496, #1392, #2078, 
#4073, and #3211 were used in the thermosalinograph (Section 2.2). 

SN Date 
yymmdd 
f0 a b c d RMS 
(mC) 
2242 50111 2997.35 3.68121134e-03 6.02950170e-04 1.62337733e-05 2.17899661e-06 0.07 
2242 41111 2997.35 3.68121113e-03 6.02952691e-04 1.62557770e-05 2.20464599e-06 0.07 
2242 40902 2997.34 3.68121142e-03 6.02944339e-04 1.62325783e-05 2.18293451e-06 0.07 
2242 40626 2997.35 3.68121105e-03 6.02955276e-04 1.62397550e-05 2.18086509e-06 0.06 
2242 40401 2997.34 3.68121397e-03 6.02939174e-04 1.62163129e-05 2.17593757e-06 0.08 
2242 40206 2997.36 3.68121397e-03 6.02950385e-04 1.62469288e-05 2.20053454e-06 0.08 
2454 50111 2885.74 3.68121209e-03 6.02189593e-04 1.68073225e-05 2.41468487e-06 0.07 
2454 41111 2885.73 3.68121193e-03 6.02184316e-04 1.68016426e-05 2.41392105e-06 0.06 
2454 40902 2885.69 3.68121232e-03 6.02166743e-04 1.67712039e-05 2.39111375e-06 0.08 
2454 40626 2885.69 3.68121195e-03 6.02159791e-04 1.67408614e-05 2.36751878e-06 0.07 
2454 40401 2885.69 3.68121482e-03 6.02168952e-04 1.67825739e-05 2.40950836e-06 0.07 
2454 40206 2885.7 3.68121479e-03 6.02176040e-04 1.68000658e-05 2.42295393e-06 0.08 
2700 50111 2972.6 3.68121232e-03 6.04822192e-04 1.65825571e-05 2.39934333e-06 0.08 
2700 41111 2972.6 3.68121197e-03 6.04821651e-04 1.65899272e-05 2.40900872e-06 0.06 
2700 40902 2972.58 3.68121238e-03 6.04814992e-04 1.65732011e-05 2.39156477e-06 0.09 
2700 40626 2972.56 3.68121206e-03 6.04791567e-04 1.65117055e-05 2.34596117e-06 0.07 
2700 40401 2972.57 3.68121493e-03 6.04810471e-04 1.65672157e-05 2.39636770e-06 0.08 
2700 40206 2972.58 3.68121481e-03 6.04821743e-04 1.65970248e-05 2.41924836e-06 0.08 
1416 50108 6234.3 3.68121511e-03 6.01744932e-04 1.47523855e-05 1.89681324e-06 0.19 
1416 41116 6234.26 3.68121451e-03 6.01724318e-04 1.47124703e-05 1.87155032e-06 0.22 
1416 40902 6234.29 3.68121255e-03 6.01758557e-04 1.48596742e-05 2.01486851e-06 0.2 
1416 40626 6234.34 3.68121379e-03 6.01751983e-04 1.47805498e-05 1.91925416e-06 0.21 
1416 40401 6234.36 3.68121483e-03 6.01770037e-04 1.48441350e-05 1.97454064e-06 0.2 
1416 40206 6234.39 3.68121414e-03 6.01779250e-04 1.48456605e-05 1.96206564e-06 0.23 
2045 050916 2443.12 3.64763417e-03 5.89821132e-04 8.72780385e-06 -2.09538278e-06 0.10 

24



2045 041012 2443.04 3.64763713e-03 5.89786065e-04 8.52269014e-06 -2.27179337e-06 0.29 
2045 040317 2443.21 3.64763817e-03 5.90004729e-04 9.00966561e-06 -1.89384962e-06 0.37 
2045 030124 2443.19 3.64763755e-03 5.90046922e-04 9.17609793e-06 -1.73405766e-06 0.28 
2045 010630 2442.94 3.64763675e-03 5.89822533e-04 8.67059662e-06 -2.25063895e-06 0.28 
2045 000908 2442.96 3.64763323e-03 5.89543392e-04 7.77856248e-06 -2.95111973e-06 0.21 
2045 000901 2443.05 3.64763446e-03 5.89779606e-04 8.53705581e-06 -2.22043394e-06 0.50 
2045 990810 2454.26 3.64491128e-03 5.89429698e-04 7.83780151e-06 -2.80829868e-06 0.20 
1496 050903 5951.32 3.68121888e-03 5.89924752e-04 1.46445105e-05 2.88655316e-06 0.17 
1496 030531 5951.07 3.68121159e-03 5.89910979e-04 1.46402233e-05 2.89014609e-06 0.22 
1496 020406 5950.97 3.68121326e-03 5.89924007e-04 1.46555677e-05 2.90029383e-06 0.21 
1496 010803 5965.19 3.67981425e-03 5.89878647e-04 1.46556176e-05 2.88953261e-06 0.18 
1496 000113 5949.21 3.68137251e-03 5.89921850e-04 1.46428791e-05 2.89432327e-06 0.21 
1496 980716 5947.26 3.68153908e-03 5.89975419e-04 1.46589621e-05 2.88623686e-06 0.20 
1392 040702 2575.49 3.64763908e-03 5.86379560e-04 9.00747869e-06 -2.50476312e-06 0.38 
1392 030603 2575.48 3.64763773e-03 5.86506294e-04 9.50040893e-06 -2.01054772e-06 0.32 
1392 020127 2575.51 3.64763443e-03 5.86539063e-04 9.55777980e-06 -2.06798694e-06 0.12 
1392 010117 2575.50 3.64764418e-03 5.86401349e-04 9.00471227e-06 2.57262161e-06 0.50 
1392 000127 2575.59 3.64763375e-03 5.86545184e-04 9.78001159e-06 -1.67704522e-06 0.20 
2078 40630 2767.79 3.68121159e-03 5.92878824e-04 1.61847564e-05 1.75681902e-06 0.04 
2078 30227 2767.84 3.68121147e-03 5.92899183e-04 1.62319487e-05 1.78868127e-06 0.03 
2078 020130 2767.93 3.68121120e-03 5.92925146e-04 1.62682614e-05 1.81029283e-06 0.03 
2078 010630 2774.47 3.67981941e-03 5.92839146e-04 1.62443042e-05 1.80670461e-06 0.04 
2078 000902 2774.00 3.67992125e-03 5.92809918e-04 1.61568922e-05 1.73539414e-06 0.03 
2078 990812 2773.49 3.68001979e-03 5.92818163e-04 1.61678036e-05 1.73277527e-06 0.02 
2078 990805 2773.38 3.68002759e-03 5.92815247e-04 1.61571052e-05 1.73369510e-06 0.03 
2078 961217 2772.55 3.68022581e-03 5.92832713e-04 1.62002729e-05 1.77796339e-06 0.03 
2078 951019 2772.32 3.68029270e-03 5.92819697e-04 1.61663533e-05 1.75679211e-06 0.03 
4073 41019 2921.95 3.68121165e-03 6.01919691e-04 1.57138499e-05 1.93432937e-06 0.04 
4073 40311 2979.74 3.68121315e-03 6.02163593e-04 1.62264620e-05 1.57341125e-06 0.05 
4073 30123 2979.81 3.68121177e-03 6.02159631e-04 1.62172842e-05 1.55965822e-06 0.04 
4073 20423 2979.82 3.68121030e-03 6.02172150e-04 1.62414413e-05 1.57818646e-06 0.05 
3211 050225 2617.142 3.64763704e-03 5.94636572e-04 1.54634049e-05 8.27296950e-07 0.07 
3211 030221 2617.226 3.64763549e-03 5.94749943e-04 1.58358837e-05 1.19318302e-06 0.10 

For each sensor, the final calibration consists of two parts: first, a single "baseline" 
calibration is chosen from among the ensemble of calibrations during the year; second, for each 
cruise a temperature-independent offset is applied to remove the temporal trend due to sensor 
drift (Table 2.3). The offset, a linear function of time, is calculated by least squares fit to the 0-30 
C average of each calibration during the year. The maximum drift correction in 2004 was less 
than 0.2 x 10-3 C. The baseline calibration is selected as the one for which the trend-corrected 
average from 0-5 C is nearest to the ensemble mean of these averages. 

A small residual pressure effect on the temperature sensors documented in Tupas et al. 
(1997) has been removed from measurements obtained with our sensors. Another correction to 
our temperature measurements was for the viscous heating of the sensor tip due to the water 
flow. This correction is thoroughly documented in Tupas et al. (1997). 

25



Dual sensors were used during each of the 2004 cruises. The temperature differences 
between sensor pairs were calculated for each cast to evaluate the quality of the data, and to 
identify possible problems with the sensors. Means and standard deviations of the differences in 
2-dbar bins were calculated from the ensemble of all casts at Station ALOHA for each cruise. 
Both sensors performed correctly during the 2004 cruises, showing temperature differences 
within expected values. The mean temperature difference as a function of pressure was typically 
less than 1 x 10-3 C, with a standard deviation of less than 0.5 x 10-3 C below 500 dbar. The 
largest variability was observed in the thermocline, with standard deviation values of up to 5 x 
10-3 C. 

Sensor #2454 

The calibrations from October 2002 through January 2005 were used to obtain a drift of 

6.1 x 10-7 C day-1 with an intercept of -3.6 x 10-5 C and a RMS residual of 2.0 x 10-4 C, and 
was used to obtain the drift correction for cruises HOT-155 through 166. When corrected for 
linear drift to 30 June 2004 (the mid-date when the sensor was used), the 6 February 2004 
calibration gave the smallest deviation in the 0-5 C temperature range from the set of all 
calibrations (also corrected for linear drift to 30 June 2004). Drift corrections were obtained 
using this calibration as a baseline. The deviation was 8.8 x 10-5 C with less than 0.2 x 10-4 C 
range of variation. The set of all calibrations had deviations in the range  5 x 10-4 C. The 
resulting drift corrections for each cruise were less than 0.2 x 10-3 C, and deemed insignificant 
(Table 2.3). 
Sensor #2700 

The calibrations from July 2000 through January 2005 indicated a decrease in the 
sensor's drift starting in 2003. The calibrations after this date were used to estimate a sensor drift 
of -1.85 x 10-7 C day-1 with an intercept of 1.1 x 10-4 C and a RMS residual of 1.1 x 10-4 C. 
This drift was used to obtain the correction for cruises HOT-155 through 166. When corrected 
for linear drift to 30 June 2004 (the midpoint of the cruise dates), the 1 April 2004 calibration 
gave the smallest deviation in the 0-5 C temperature range from the set of calibrations obtained 
in 2004 (also corrected for linear drift to 30 June 2004). The deviation was 3.8 x 10-5 C with 
less than 0.2 x 10-4 C range of variation. The set of all calibrations had deviations in the range  
3 x 10-4 C. The resulting drift corrections for each cruise were less than 0.05 x 10-3 C, and 
deemed insignificant (Table 2.3). 

26



Sensor #2242 

This sensor was not used during 2004. The calibrations from January 2001 through 
January 2005 indicated a decrease in the sensor's drift rate starting in March 2003. Using the 
calibrations after this date yielded a linear drift of 1.38 x 10-6 C day-1, with an intercept of 3.8 x 
10-5 C, and 6.5 x 10-5 C RMS residuals. 

Sensor #1416 

 This sensor was not used during 2004. This sensor has maintained a constant and 
uninterrupted drift for a long time, however the calibrations from April 1996 through January 
2005 indicated a slight decrease in the sensor's drift starting in October 2002. The calibrations 
after this date yielded a linear drift of 1.73 x 10-6 C day-1, with an intercept of 4.6 x 10-5 C, and 

8.4 x 10-5 C RMS residuals. 
Table 2.3: Temperature (T) and Conductivity (C) sensor corrections including the thermal 
inertia parameter (a). Dual temperature and conductivity sensors were used in all cruises. The 
last column indicates which T-C sensor pairs data is reported. 

Cruise 

HOT-155 
HOT-155 
HOT-156 
HOT-156 
HOT-157 
HOT-157 
HOT-158 
HOT-158 
HOT-159 
HOT-159 
HOT-160 
HOT-160 
HOT-161 
HOT-161 
HOT-162 
HOT-162 
HOT-163 
HOT-163 
HOT-164 
HOT-164 
HOT-165 
HOT-165 
HOT-166 
HOT-166 

T sensor # T Correction ( C) C sensor # a Data reported 
2700 0.000013 2725 0.020 All casts 
2454 -0.000009 2541 0.020 
2700 0.000007 2725 0.020 All casts 
2454 0.000012 2541 0.020 
2700 0.000002 2725 0.012 All casts 
2454 0.000026 2541 0.037 
2700 -0.000004 2725 0.020 All casts 
2454 0.000046 2541 0.012 
2700 -0.000009 2725 0.020 All casts 
2454 0.000063 2541 0.020 
2700 -0.000014 2725 0.020 All casts 
2454 0.000080 2541 0.020 
2700 -0.000019 2725 0.020 All casts 
2454 0.000097 2541 0.020 
2700 -0.000025 2725 0.020 All other casts 
2454 0.000118 2541 0.020 Station 1 cast 1 
2700 -0.000033 2725 0.020 All casts 
2454 0.000144 2541 0.020 
2700 -0.000039 2725 0.020 All casts 
2454 0.000164 2541 0.020 
2700 -0.000044 2725 0.020 All casts 
2454 0.000181 2541 0.020 
2700 -0.000049 2725 0.020 All casts 
2454 0.000195 2541 0.020 

27



2.1.2.3 Conductivity 
Two conductivity sensors were used during the 2004 cruises #2725, and #2541. Sensor 
#2218 was backup sensor. The history of the sensors is well documented in Santiago-Mandujano 
et al. (2002, 2001, 1999), Tupas et al. (1993, 1994a, 1995, 1997, 1998) and Karl et al. (1996). 
The dual sensor configurations are shown in Table 2.3. As mentioned earlier, only the data from 
the most reliable sensor (and its corresponding temperature sensor pair, as shown in Table 2.3) 
are reported here. 

For each sensor, the nominal calibrations were used for data acquisition, and a final 
calibration was determined empirically from salinities of discrete water samples acquired during 
each cast. Prior to empirical calibration, conductivity was corrected for thermal inertia of the 
glass conductivity cell as described in Chiswell et al. (1990). Table 2.3 lists the value of the a 
parameter used for each cruise. 

Procedures for preliminary screening of bottle samples and empirical calibration of the 
conductivity cell are described in Tupas et al. (1993, 1994a). For cruises HOT-155 through -166, 
the standard deviation cutoff values for screening of bottle salinity samples were: 0.0035 (0-150 
dbar), 0.0048 (151-500 dbar), 0.0020 (501- 1050 dbar), and 0.0011 (1051-5000 dbar). 

The conductivity calibration coefficients (b0, b1, b2) derived from the least squares fit 
(.C = b0 + b1C + b2C2) to the CTD-bottle conductivity differences (.C) as a function of 
conductivity (C) are given in Table 2.4. Three cruises during 2004 required a quadratic 
calibration (HOT-156, 158, and 163). The quality of the CTD calibration is illustrated in Figure 
2.2, which shows the differences between the corrected CTD salinities and the bottle salinities 
used for calibration as a function of pressure for each cruise. The calibrations are best below 500 
dbar because the weaker vertical salinity gradients at depth lead to less error when the bottle and 
CTD pressures are slightly mismatched. 

The final step of conductivity calibration was a cast-dependent bias correction as 
described in Tupas et al. (1993) to allow for drift during each cruise or for sudden offsets due to 
fouling (Table 2.5). Note that a change of 1 x 10-4 Siemens m-1 in conductivity is approximately 
equivalent to 0.001 in salinity. Table 2.6 gives the mean and standard deviations for the final 
calibrated CTD minus bottle samples shown in Figure 2.2. 

Conductivity differences between sensor pairs were calculated the same way as for the 
temperature sensors (Section 2.1.2.2). The range of variability as a function of pressure was 
about  1 x 10-4 Siemens m-1, with a standard deviation of less than 0.5 x 10-4 Siemens m-1 
below 500 dbar, from the ensemble of all the cruise casts. The largest variability was in the 
halocline, with standard deviations reaching up to 5 x 10-4 Siemens m-1 between 50 and 300 
dbar. 

28



Table 2.4: Conductivity calibration coefficients 

Cruise Sensor # b0 b1 b2 
HOT-155 2725 0.000023 -0.000007 -
HOT-155 2541 0.000160 0.000055 -
HOT-156 2725 0.003618 -0.001764 0.000214 
HOT-156 2541 0.004359 -0.002044 0.000248 
HOT-157 2725 0.000233 -0.000028 -
HOT-157 2541 0.000372 -0.000022 -
HOT-158 2725 0.003802 -0.001856 0.000229 
HOT-158 2541 0.005785 -0.002756 0.000334 
HOT-159 2725 0.000267 -0.000023 -
HOT-159 2541 0.000446 -0.000035 -
HOT-160 2725 0.000093 0.000019 -
HOT-160 2541 0.000269 0.000011 -
HOT-161 2725 0.000624 -0.000145 -
HOT-161 2541 0.000790 -0.000145 -
HOT-162 2725 0.000482 -0.000119 -
HOT-162 2541 0.000383 -0.000089 -
HOT-163 2725 0.003069 -0.001433 0.000165 
HOT-163 2541 0.002382 -0.001172 0.000130 
HOT-164 2725 0.000173 -0.000043 -
HOT-164 2541 0.000166 -0.000063 -
HOT-165 2725 0.000496 -0.000143 -
HOT-165 2541 0.000409 -0.000147 -
HOT-166 2725 0.000339 -0.000104 -
HOT-166 2541 0.000196 -0.000093 -

Table 2.5: Individual cast conductivity corrections (units are Siemens m-1) 

Cruise Station Cast C Correction 
HOT-155 2 1 0.000046 
HOT-157 2 1 0.000038 
HOT-160 2 2 0.000066 
HOT-160 2 16 0.000086 
HOT-161 2 2 -0.000043 
HOT-164 2 2 0.000044 

29



Table 2.6: CTD-Bottle salinity comparison for each cruise 

Cruise 

HOT-155 
HOT-155 
HOT-156 
HOT-156 
HOT-157 
HOT-157 
HOT-158 
HOT-158 
HOT-159 
HOT-159 
HOT-160 
HOT-160 
HOT-161 
HOT-161 
HOT-162 
HOT-162 
HOT-163 
HOT-163 
HOT-164 
HOT-164 
HOT-165 
HOT-165 
HOT-166 
HOT-166 

0-4800 dbar 500-4800 dbar 

Sensor # Mean St. dev Mean St. dev 

2725 -0.0001 0.0019 0.0000 0.0010 
2541 -0.0001 0.0019 0.0000 0.0009 
2725 0.0000 0.0016 0.0001 0.0012 
2541 0.0000 0.0016 0.0001 0.0010 
2725 0.0000 0.0019 0.0001 0.0010 
2541 0.0000 0.0018 0.0001 0.0009 
2725 0.0000 0.0019 0.0000 0.0013 
2541 0.0000 0.0021 0.0000 0.0012 
2725 0.0000 0.0025 0.0001 0.0012 
2541 -0.0001 0.0026 0.0001 0.0011 
2725 -0.0001 0.0022 -0.0001 0.0010 
2541 -0.0001 0.0022 -0.0002 0.0010 
2725 0.0001 0.0024 0.0007 0.0009 
2541 0.0001 0.0025 0.0007 0.0010 
2725 0.0000 0.0025 0.0007 0.0011 
2541 0.0000 0.0024 0.0007 0.0010 
2725 0.0000 0.0024 0.0001 0.0012 
2541 0.0000 0.0023 0.0001 0.0012 
2725 0.0000 0.0019 0.0001 0.0013 
2541 0.0000 0.0017 0.0000 0.0012 
2725 0.0000 0.0023 0.0002 0.0013 
2541 0.0000 0.0025 0.0002 0.0011 
2725 0.0000 0.0022 0.0003 0.0007 
2541 0.0000 0.0023 0.0002 0.0010 

30



31 
-0.01 0 0.01 
5000 
4000 
3000 
2000 
1000
0 
HOT-155 
Pressure [dbar] 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
HOT-156 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
HOT-157 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
5000 
4000 
3000 
2000 
1000
0 
HOT-158 
Pressure [dbar] 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
HOT-159 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
HOT-160 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
5000 
4000 
3000 
2000 
1000
0 
HOT-161 
Pressure [dbar] 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
HOT-162 
Salinity (CTD-Bottle) 
-0.01 0 0.01 
HOT-163 
Salinity (CTD-Bottle) 
Figure 2.2: Difference between calibrated CTD salinities and bottle salinities for each cruise and 
all casts at Station ALOHA in 2004. 

HOT-164 HOT-165 HOT-166 

Pressure [dbar] 

0 
1000 
2000 
3000 
4000 
5000 


-0.01 0 0.01 -0.01 0 0.01 -0.01 0 0.01 
Salinity (CTD-Bottle) Salinity (CTD-Bottle) Salinity (CTD-Bottle) 

Figure 2.2: continued 

32



2.1.2.4 Oxygen 
During the 2004 cruises our three Sea-Bird SBE-43 oxygen sensors were used: #43134, 
#43262, and #43325. The history of these sensors is documented in Santiago-Mandujano et al. 
(2002, 2001, and 1999). Sensor's #43262 membrane was found thorn during a routine calibration 
at Sea-Bird in February 2004 and was repaired. The same sensor showed drift during cruise 
HOT-158 and it had its lid and membrane assembly replaced at Sea-Bird, as well as its 
electrolyte reservoir re-backfilled. 

Water bottle oxygen data were screened and the oxygen sensors were empirically 
calibrated following procedures described previously (Winn et al. 1991; Tupas et al., 1993). The 
analysis of water bottle samples is described in Section 2.5.1. The calibration procedure follows 
Owens and Millard (1985), and consists of fitting a non-linear equation to the CTD oxygen 
current and oxygen temperature. The bottle values of dissolved oxygen and the downcast CTD 
observations at the potential density of each bottle trip were grouped together for each cruise to 
find the best set of parameters with a non-linear least squares algorithm. Two sets of parameters 
were usually obtained per HOT cruise, corresponding to the casts at Stations 1and 2 (calibrations 
coefficients from cast 2 are also used to calibrate the casts at stations 6, 50 and 51). The 
calibration procedure for the Sea-Bird SBE-43 sensors is documented in Santiago-Mandujano et 
al. (2001). 

Table 2.7 shows the mean and standard deviation for the calibrated CTD oxygen minus 
water sample residuals for each cruise. Dual sensors were used during cruises, but only the 
sensor whose data were deemed more reliable is reported. 

Table 2.7a: CTD-Bottle dissolved oxygen per cruise at Station Kahe (mol kg-1). Station 
Kahe was not visited during cruise 166. 

Cruise Sensor Mean SD 
HOT-155 43325 0.00 0.54 
HOT-156 43325 0.00 0.88 
HOT-157 43325 0.00 0.66 
HOT-158 43325 0.00 0.64 
HOT-159 43325 0.00 0.61 
HOT-160 43325 0.00 0.69 
HOT-161 43325 0.00 0.64 
HOT-162 43262 0.00 0.60 
HOT-163 43325 0.00 0.59 
HOT-164 43325 0.01 0.42 
HOT-165 43325 0.00 0.56 

0 to 1500 dbar 

33



Table 2.7b: CTD-Bottle dissolved oxygen per cruise at Station ALOHA (mol kg-1). 

Cruise Sensor Mean SD Mean SD 
HOT-155 43325 0.01 1.00 0.03 0.94 
HOT-156 43325 0.01 0.78 0.03 0.69 
HOT-157 43325 0.09 0.86 0.02 0.70 
HOT-158 43325 0.00 0.66 0.11 0.57 
HOT-159 43325 0.14 0.83 0.10 0.57 
HOT-160 43325 0.00 0.70 -0.07 0.75 
HOT-161 43325 0.05 0.45 0.10 0.40 
HOT-162 43325 0.09 0.86 0.07 0.63 
HOT-163 43325 0.15 0.78 0.20 0.63 
HOT-164 43325 0.01 0.42 0.00 0.45 
HOT-165 43325 0.05 0.72 0.07 0.63 
HOT-166 43325 0.15 0.74 0.18 0.68 

0 to 4800 dbar 500 to 4800 dbar 

2.1.2.5 Fluorescence (Chloropigment) 
Fluorescence was measured with a Sea-Point chlorophyll fluorometer (#2440 and #2441). 
The data was collected using the Sea-Bird CTD system. Fluorescence traces were collected on 
as many casts as possible. Because an absolute radiometric standard is not available for 
fluorometers, instrument drift was corrected via calibration with bottle fluorometric chlorophyll 
a plus accessory pheopigments analyzed using a Turner Designs Model 10-AU fluorometer as 
described in Section 2.5.6.1. A linear relationship of the form, Vchl = bVfluor + a, was used to 
convert all fluorescence data to chloropigment. 

2.1.3 Discrete salinity 
Salinity samples were collected, stored and analyzed as described in Tupas et al. (1993). 
IAPSO samples were measured to standardize the salinometer, and samples from a large batch of 
secondary standard (substandard) seawater were measured after every 24 bottle samples of 
each cruise to detect drift in the salinometer. Standard deviations of the secondary standard 
measurements were less than  0.001 for all the cruises (Table 2.8). 

The secondary standard seawater batches are made from 60 liters of seawater taken from 
a depth of 1000 m from Station ALOHA. Secondary standard batches #33, 34, and 35 were 
prepared on January 27, 2004, April 27, 2004, and on August 24, 2004, respectively. 

34



Table 2.8: Precision of salinity measurements using secondary lab standards 

Cruise Mean Salinity  SD # Samples Substandard Batch # IAPSO Batch # 
HOT-155 34.49329  0.00042 24 33 P141 
HOT-156 34.49299  0.00026 27 33 P141 
HOT-157 34.49276  0.00045 24 33 P141 
HOT-158 34.48171  0.00032 30 34 P141 
HOT-159 34.48041  0.00038 26 34 P141 
HOT-160 34.48074  0.00032 29 34 P141 
HOT-161 34.47936  0.00029 16 34 P143 
HOT-162 34.46392  0.00019 21 35 P143 
HOT-163 34.46467  0.00035 22 35 P143 
HOT-164 34.46438  0.00034 28 35 P143 
HOT-165 34.46445  0.00042 30 35 P143 
HOT-166 34.46413  0.00048 29 35 P143 

2.2 Thermosalinograph 
2.2.1 Data Acquisition 
Continuous near-surface salinity and temperature data were collected at ten second 
intervals during every 2004 HOT cruise (HOT-155 through HOT-166) using Sea-Bird 
thermosalinograph and temperature sensors aboard the R/V Ka'imikai-o-Kanaloa and the R/V 
Kilo Moana. The details of each thermosalinograph system varied from ship to ship, but both 
systems were composed of a remote temperature sensor to measure near-surface temperatures at 
the intake of the ship's uncontaminated seawater supply in conjunction with a thermosalinograph 
sensor that measured both conductivity and temperature. Salinity of the seawater was then 
calculated using the internal temperature and conductivity as well as the internal pressure of the 
pump. Navigation data was collected at 10 second intervals and merged with the 
thermosalinograph data stream. The 2004 HOT cruises are listed below in Table 2.9 along with 
the ship used for each cruise and the serial numbers of the Sea-bird sensors used to collect the 
thermosalinograph data. 

Thermosalinograph conductivities were calibrated using bottle salinity samples 
periodically taken (approximately every 4 hours) from the continuous seawater line outtake near 
to the thermosalinograph. The thermosalinograph data from each cruise were also compared 
with CTD temperature and conductivity data collected at the same time and from near the same 
depth as the thermosalinograph data for a final data quality control. 

35



Table 2.9: HOT 2004 Thermosalinograph Sensors 

Cruise No. Ship Sensor S/N 
Remote T Internal T and C 
HOT-155 
HOT-156 
HOT-157 
HOT-158 
HOT-159 
HOT-160 
HOT-161 
HOT-162 
HOT-163 
HOT-164 
HOT-165 
HOT-166 
KOK 
KOK 
KM 
KOK 
KOK 
KOK 
KOK 
KOK 
KOK 
KOK 
KOK 
KOK 
4073 
4073 
0169 
2078 
2078 
2078 
1496 
1496 
1496 
1496 
1496 
1496 
2045 
2045 
3211 
1392 
1392 
1392 
2045 
2045 
1392 
1392 
2045 
1392 

KOK = R/V Ka'imikai-o-Kanaloa 
KM = R/V Kilo Moana 


The thermosalinograph system aboard the R/V Ka'imikai-o-Kanaloa consisted of an 
internal SBE-21 Seacat thermosalinograph unit along with a SBE-3 external temperature sensor 
installed in a sea chest at the bow of the ship. The depth of the seawater intake was 
approximately 3 meters below the surface, and the internal pressure of the pump was 10 dbar. 

The thermosalinograph system aboard the R/V Kilo Moana consisted of an internal SBE21 
Seacat thermosalinograph unit along with a SBE-38 external temperature sensor installed in 
the bow thruster chamber close to the seawater intake. The depth of the intake was 8 meters 
below the surface, and the internal pressure of the pump was 6 dbar. The external temperature 
sensor was situated just aft of the seawater intake pump and as a result the resultant water 
temperatures were higher than values obtained with the CTD at the same depth as the intake and 
bucket temperature measurements made at the intake. External temperature data for HOT-157 
were adjusted using the 8 dbar CTD measurements and subsequently flagged as uncalibrated. 

2.2.2 Data processing and sensor calibration 
2.2.2.1 Nominal Calibration 
2.2.2.1.1 Temperature 
The Sea-Bird internal and external temperature sensors (Table 2.9 above) have been 
calibrated at Sea-Bird (Table 2.2), and since these sensors are the same type as used for the CTD 
measurements, the same procedure for drift estimation was followed (see Section 2.1.2.2). The 

36



SBE-38 temperature sensor #0169 uses a calibration equation different than equation (1), and its 
calibration coefficients are shown in Table 2.10 (see below) 

Sensor #4073 

A temperature drift rate of 1.53 x 10-6 C day-1 was determined for remote temperature 
sensor #4073 using the 23 April 2002 , 23 January 2003, and 11 March 2004 calibrations. 
Temperatures were calculated with the 23 January 2003 baseline calibration. Drift corrections 
were not applied to the data for this sensor, as they are smaller than 1 mC and inconsequential. 

Sensor #2045 

A temperature drift rate of -2.28 x 10-7 C day-1 was determined for internal temperature 
sensor #2045 using the 11 October 1995, 30 July 1996, 28 July 1998, 10 August 1999, 08 
September 2000, 30 June 2001, 24 January 2003, 17 March 2004, 12 October 2004, and 16 
September 2005 calibrations. Temperatures were calculated with the 24 January 2003 baseline 
calibration for HOT-155 and 156, 17 March 2004 for HOT-161 and 162, and 12 October 2004 
for HOT-165. Drift corrections were not applied to the data for this sensor, as they are smaller 
than 1 mC and inconsequential. 

Sensor #3211 

A temperature drift rate of 9.29 x 10-7 C day-1 was determined for internal temperature 
sensor #3211 using the 21 February 2003 and 25 February 2005 calibrations. Temperatures 
were calculated with the 21 February 2003 baseline calibration. Drift corrections were not 
applied to the data for this sensor, as they are smaller than 1 mC and inconsequential. 

Sensor #2078 

A temperature drift rate of 2.31 x 10-6 C day-1 was determined for remote temperature 
sensor #2078 using the 08 September 2000, 30 June 2001, 30 January 2002, 27 February 2003, 
and 30 June 2004 calibrations. Temperatures were calculated with the 27 February 2003 
baseline calibration. Drift corrections were not applied to the data for this sensor, as they are 
smaller than 1 mC and inconsequential. 

Sensor #1392 

A temperature drift rate of 3.70 x 10-7 C day-1 was determined for internal temperature 
sensor #1392 using the 20 August 1997, 28 August 1997, 27 January 2000, 27 January 2002, 03 
June 2003, and 07 October 2005 calibrations. Temperatures were calculated with the 03 June 
2003 baseline calibration. Drift corrections were not applied to the data for this sensor, as they 
are smaller than 1 mC and inconsequential. 

Sensor #1496 

A temperature drift rate of -1.96 x 10-6C day-1 was determined for remote temperature 
sensor #1496 using the 13 January 2000, 18 January 2001, 03 August 2001, 06 April 2002, 31 

37



May 2003, and 03 September 2005 calibrations. Temperatures were calculated with the 31 May 
2003 baseline calibration. Drift corrections were not applied to the data for this sensor, as they 
are smaller than 1 mC and inconsequential. 

Temperature sensor #0169 is a SBE-38 model and uses the following equation to convert 
the instrument output (n) to temperature (in C) : 

temperature = 1/{a0+a1[ln(n)]+a2[ln2(n)]+a3[ln3(n)]}-273.15 

Sensor #0169 

A temperature drift rate of 1.65 x 10-7 C day-1 was determined for remote temperature 
sensor #0169 using the 28 February 2003 and 25 February 2005 calibrations. Temperatures 
were calculated with the 28 February 2003 baseline calibration. Drift corrections were not 
applied to the data for this sensor, as they are smaller than 1 mC and inconsequential. 

Table 2.10: Calibration coefficients for Sea-Bird temperature sensors SBE-38. RMS residuals 
from calibration give an indication of the quality of calibration. 

SN Date 
yymmdd 
a0 a1 a2 a3 RMS 
(mC) 
0169 050225 -3.116768e-05 2.783157e-04 -2.530733e-06 1.646721e-07 0.03 
0169 030228 -3.884467e-05 2.801349e-04 -2.674289e-06 1.684452e-07 0.03 

2.2.2.1.2 Conductivity 
Three different conductivity sensors were used to collect thermosalinograph data for the 
2004 HOT cruises (Table 2.9). All the conductivity data were nominally calibrated with 
coefficients obtained at Sea-Bird, however all the final salinity data were calibrated against 
bottle data as explained below. 

2.2.2.2 Processing 
The thermosalinograph data were screened for gross errors with upper and lower bounds 
of 35 and 18 C for temperature and 6 and 3 Siemens m-1 for conductivity. There were a total of 
3 gross errors detected during the twelve 2004 HOT cruises, with a typical cruise containing 
approximately 30,000-40,000 data points. The remaining data were subsequently screened for 
bad or suspicious points and were ascribed to factors such as air bubbles entering the 
thermosalinograph system, electrical surges from the power supply, biological fouling of the 
thermosalinograph, etc. A quality control system has been established so that each temperature 
and salinity point is given a flag to determine whether the data are good, suspect, or bad. A 5point 
running median filter was used to detect one or two point temperature and conduct glitches 

38



in the thermosalinograph data. Glitches in temperature and conductivity detected by the 5-point 
median filter were immediately replaced by the median. Threshold values of 0.3 C for 
temperature and 0.1 Siemens m-1 for conductivity were used for the median filter. No more than 
a few points were replaced after running the median filter. A 3-point triangular mean filter was 
used to smooth the temperature and conductivity data from all the cruises after they had gone 
through glitch detection. The temperature and conductivity record was manually inspected to 
further flag suspect or bad data. 

The number of thermosalinograph data points flagged as suspicious or bad per cruise 
ranged from 0 to 10235, with the majority of the flags applied to the conductivity data. Most 
sections of flagged data were relatively small and were associated with air bubbles entering the 
thermosalinograph system during rough weather or with data spikes resulting from electrical 
surge from a pump used during the bottle sampling operation. Strong winds and rough seas 
particularly around Kaena Point during transit to ALOHA can introduce bubbles resulting in 
large periods of suspect data. During HOT-157 conducted on the R/V Kilo Moana the valve 
supplying the uncontaminated seawater to the external sensor was inadvertently left closed for 
the whole cruise. The internal temperature data were reported in place of the external 
temperature data, after comparing it with the CTD temperature data, and applying an offset of 0.2184
C. The resulting values were flagged as uncalibrated (flag code '1'). 

An estimate of the noise in thermosalinograph data was performed to evaluate quality. A 
101-point running mean (about 17 min. at 10 sec. sampling rate) was applied to the 
thermosalinograph salinities and external temperatures, and the standard deviations of the 
residuals from the original data were used as an estimate of the data noise. Only data taken 
during periods of near-constant salinity or temperature were included in the estimated to avoid 
large residuals resulting in sections of large variability. Noise estimates were obtained for 
cruises HOT-155 through HOT-166 (Table 2.11). 

Table 2.11: Noise Estimates for thermosalinograph data during 2004 cruises 

Cruise Salinity Noise (psu) Temperature Noise 
(C) 
HOT-155 0.0016 0.0033 
HOT-156 0.0021 0.0055 
HOT-157a 0.0011 0.0032 
HOT-158 0.0014 0.0053 
HOT-159 0.0027 0.0078 
HOT-160 0.0015 0.0066 
HOT-161 0.0023 0.0048 
HOT-162 0.0019 0.0058 
HOT-163 0.0010 0.0069 
HOT-164 0.0039 0.0042 
HOT-165 0.0016 0.0034 
HOT-166 0.0010 0.0031 
a: aboard R/V Kilo Moana 
39 


2.2.2.3 Conductivity Calibration 
The thermosalinograph salinity was calibrated by comparing it to bottle salinity samples 
drawn from the plumbing near the thermosalinograph. Bottle salinity samples were analyzed as 
described in Section 2.1.3. 

The bottle sampling area aboard the R/V Ka'imikai-o-Kanaloa and R/V Kilo Moana was 
located immediately next to the thermosalinograph used to calculate salinity; therefore 
thermosalinograph data were extracted within 15 seconds around the bottle sample time. 

As in previously reported cruises (Tupas et al., 1997) a cubic spline was fit to the time-
series of the differences between the bottle conductivity and the thermosalinograph conductivity 
separately for all the 2004 HOT cruises. The correction of the thermosalinograph conductivities 
was obtained from this fit. Salinity was calculated using these corrected conductivities, 
thermosalinograph temperatures, and the pressure of the pump. The mean values for the salinity 
bottle minus final calibrated thermosalinograph were less than  5 x 10-6 for all cruises, with 
standard deviations shown in Table 2.12. 

Table 2.12: Bottle-Thermosalinograph salinity comparison during HOT 2004 cruises 

Cruise Sensor # Standard Deviation 
HOT-155 
HOT-156 
HOT-157 
HOT-158 
HOT-159 
HOT-160 
HOT-160 
HOT-162 
HOT-163 
HOT-164 
HOT-165 
HOT-166 
2045 
2045 
3211 
1392 
1392 
1392 
2045 
2045 
1392 
1392 
2045 
1392 
0.0020 
0.0038 
0.0012 
0.0024 
0.0025 
0.0031 
0.0018 
0.0038 
0.0015 
0.0027 
0.0070 
0.0025 

During HOT-164 the thermosalinograph experienced some problems resulting in two 
distinct shifts in conductivity data. The data were split into three sections and calibrated against 
the bottle salinity samples individually before being merged into one data set. 

40 


2.2.2.4 Comparison with the CTD Data 
The external temperature and the calibrated thermosalinograph salinity data collected 
during CTD casts were compared with the downcast CTD temperature and salinity data from a 
similar depth as the intake as an additional quality control. This procedure was conducted in the 
same manner as previously reported HOT cruises. The thermosalinograph data were averaged 
using data sampled one minute after the acquisition time of the CTD sample. Mean differences 
with the CTD were no greater than 0.006C in temperature and 0.003 psu in salinity for all 
2004 HOT cruises (Table 2.13). 

Table 2.13: CTD- External Temperature and CTD  Thermosalinograph salinity comparison 
during HOT 2004 cruises. 

Cruise Sensor # 
CTD-ExternalTemperature(C) Sensor # 
CTD-
ThermosalinographSalinity 
HOT-155 
HOT-156 
HOT-157 
HOT-158 
HOT-159 
HOT-160 
HOT-160 
HOT-162 
HOT-163 
HOT-164 
HOT-165 
HOT-166 
4073 
4073 
0169 
2078 
2078 
2078 
1496 
1496 
1496 
1496 
1496 
1496 
-0.001 
-0.006 
0.000* 
-0.006 
-0.004 
-0.004 
-0.002 
-0.004 
0.003 
-0.002 
-0.005 
-0.002 
2045 
2045 
3211 
1392 
1392 
1392 
2045 
2045 
1392 
1392 
2045 
1392 
-0.002 
-0.001 
0.001 
-0.001 
-0.003 
-0.002 
0.001 
0.000 
0.003 
0.000 
-0.002 
-0.001 

 Onboard Kilo Moana internal temperature calibrated against CTD 
data was used. 
2.3 Meteorology 
Wind speed and direction, atmospheric pressure, wet- and dry-bulb air temperature, sea 
surface temperature (SST), cloud cover and weather code were recorded at four-hour intervals 
while at Station ALOHA by the science personnel. Continuous wind velocity measurements 
recorded at 5-min intervals from the anemometers on the R/V Kaimikai-o-Kanaloa and on the 
R/V Kilo Moana were also available. 

Meteorological observations were also obtained every four hours by the ship's officers on 
the bridge of the R/V Kaimikai-o-Kanaloa throughout each cruise. 

41



Also available were hourly atmospheric pressure, air temperature, SST, and wind 
velocities from NDBC buoy #51001 (23.4N, 162.3W). The buoy was operating intermittently 
during April, and was not in operation during part of May 2004. 

The time-series of shipboard observations obtained by the science group was plotted and 
obvious outliers were identified and flagged. The SST-dry air temperature and wet-dry air 
temperature plots also helped to identify outliers. Bad data points were often replaced with the 
data collected on the bridge. Outliers in the shipboard pressure, air temperature, SST, and wind 
observations were detected by comparison with the buoy data. 

2.4 ADCP Measurements 
Upper ocean currents were measured during HOT-155, 156, and 158 through 166 cruises 
using the ADCP mounted on the R/V Ka'imikai-o-Kanaloa (RD Instruments model VM-150). 
ADCP velocities were corrected for gyro compass errors as measured by the Ashtec 3DF GPS 
attitude sensor. There were no significant data recording gaps. GPS navigation (differential or 
PCODE) was available throughout all cruises. Rough weather or seas on northward transits 
caused reduced returns on some of the cruises. These conditions resulted in velocity bias in the 
direction of ship's motion. Biased regions have been edited out, and will therefore appear as gaps 
in the plots. Gaps in the on-station data during some of the cruises are due to excursions to 
retrieve the primary productivity array and floating sediment traps. HOT-157 was conducted on 
the R/V Kilo Moana, which did not have an ADCP. 

2.5 Biogeochemical Measurements 
At Stations Kahe, ALOHA and Kaena , water samples for chemical analyses were 
collected from discrete depths using 12 liter PVC bottles with nylon coated internal springs as 
closing mechanisms. Sampling strategies and procedures are well documented in the previous 
data reports and in the HOT Program Field and Laboratory Protocols manual. This report 
contains only a subset of the total database, which can be extracted electronically over the 
Internet (hahana.soest.hawaii.edu/hot/hot_jgofs.html). To assist in the interpretation of these 
data and to save users the time to estimate the precision of individual chemical analysis, we have 
summarized precision estimates from replicate determinations for selected constituents on each 
HOT cruise in 2004. 

2.5.1 Dissolved Oxygen 
Dissolved oxygen samples were collected and analyzed using a computer-controlled 
potentiometric end-point titration procedure as described in Tupas et al. (1997). As in previous 
years we measured, using a calibrated digital thermistor, the temperature of the seawater sample 
at the time the iodine flask was filled. This was done to evaluate the magnitude of sample 
temperature error that affects the calculation of oxygen concentrations in units of mol kg-1. 
Figure 2.3 (upper panel) shows a plot of the difference between sample temperature and potential 
temperature computed from the in situ temperature measured at the time of bottle trip, versus 

42



pressure. Figure 2.3 (lower panel) shows a plot of the difference between oxygen 
concentrations calculated using the sample temperature and potential temperature versus 
pressure. The depth dependent variability in . oxygen is a result of: 1) bottle warming as the 
rosette is brought up through the water column 2) warm air entering the niskin bottle as samples 
are being taken and 3) evaporative cooling that occurs while on-deck as bottles are waiting to be 
sampled. 

Precision of the Winkler titration method is presented in Table 2.14. The pooled annual 
mean CV of our oxygen analyses in 2004 was 0.16 %, which was calculated by averaging the 
mean CV of N-triplicate samples on each cruise. Oxygen concentrations measured over the 16 
years of the program are plotted at three constant potential density horizons in the deep ocean 
along with their mean and 95 % confidence intervals (Figure 2.4 [upper panel]). These results 
indicate that analytical consistency has been maintained over the past 16 years of the HOT 
program. 

Table 2.14: Precision of Winkler titration method during 2004 

HOT 
Dissolved O2 
Mean CV 
(%) 
Mean SD 
(mol kg-1) N 
155 
156 
157 
158 
159 
160 
161 
162 
163 
164 
165 
166 
0.17 
0.15 
0.10 
0.09 
0.12 
0.22 
0.12 
0.14 
0.16 
0.14 
0.23 
0.30 
0.32 
0.28 
0.20 
0.17 
0.21 
0.38 
0.22 
0.23 
0.28 
0.25 
0.37 
0.44 
8 
9 
6 
7 
8 
8 
5 
8 
8 
8 
8 
6 
Mean 0.16 0.28 11 

2.5.2 Dissolved Inorganic Carbon and Titration Alkalinity 
Samples for dissolved inorganic carbon (DIC) were measured using a Single Operator 
Multi-parameter Metabolic Analyzer (SOMMA) which was manufactured at the University of 
Rhode Island and standardized at the Brookhaven National Laboratory. The pooled annual CV 
of the DIC analyses during 2004 was 0.04 % (Table 2.15). It was calculated by averaging the 
mean CV of N-duplicate samples on each cruise. Total (titration) alkalinity (Talk) was 
determined using the modified Gran titration method as described in Tupas et al. (1997). The 
pooled annual CV of the alkalinity analyses during 2004 was 0.08 % (Table 2.15). The accuracy 
of DIC and alkalinity measurements was established with certified reference materials (CRMs) 
obtained from Andrew Dickson at Scripps Institution of Oceanography. 

43



44 
-3 -2 -1 0 1 2 3 4 5 6 7 
5000 
4500 
4000 
3500 
3000 
2500 
2000 
1500 
1000 
500 
0 
HOT 155-166 Station 2 
. Temperature [ oC] 
Pressure [dbar] 
-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 
5000 
4500 
4000 
3500 
3000 
2500 
2000 
1500 
1000 
500 
0 
HOT 155-166 Station 2 
. Oxygen [mol kg-1] 
Pressure [dbar] 
Figure 2.3: [Upper panel] Difference between sample temperature at the time of sample 
collection and potential temperature calculated from in situ temperature at the time of bottle trip. 
[Lower panel] Difference in oxygen concentration corrected for temperatures measured at the 
time of sample collection and potential temperature calculated from in situ temperature. 

Table 2.15: Precision of DIC and Total Alkalinity analyses during 2004 

HOT 
DIC Talk 
Mean CV 
(%) 
Mean SD 
(mol kg-1) N Mean CV 
(%) 
Mean SD 
(eq kg-1) N 
155 
156 
157 
158 
159 
160 
161 
162 
163 
164 
165 
166 
0.04 
0.01 
0.06 
0.01 
0.02 
0.03 
0.03 
0.01 
0.17 
0.02 
0.08 
0.01 
0.96 
0.22 
1.25 
0.25 
0.44 
0.59 
0.65 
0.19 
3.49 
0.37 
1.95 
0.16 
3 
3 
3 
3 
3 
4 
3 
4 
4 
3 
4 
3 
0.10 
0.17 
0.09 
0.09 
0.05 
0.20 
0.05 
0.04 
0.10 
0.04 
0.06 
0.02 
2.20 
3.85 
2.22 
2.03 
1.17 
4.50 
1.16 
0.96 
2.24 
1.06 
1.41 
0.53 
2 
2 
3 
3 
2 
3 
3 
2 
3 
3 
3 
2 
Mean 0.04 0.88 12 0.08 1.94 12 

2.5.3 Inorganic Nutrients 

2.5.3.1 Standard Methods 

Samples for the determination of dissolved inorganic nutrient concentrations (soluble 
reactive phosphorus, [nitrate+nitrite] and silicate) were collected as described in Tupas et al. 
(1993). Analyses were conducted on a four-channel Technicon Autoanalyzer II continuous flow 
system at the University of Hawaii Analytical Services Facility. The average precisions during 
2000 from duplicate analyses are given in Table 2.16. Figures 2.4-2.5 show the mean and 95% 
confidence limits of nutrient concentrations measured at three potential density horizons for the 
first 12 years of the program. In addition to standard automated nutrient analyses, specialized 
chemical methods are used to determine concentrations of nutrients that are normally below the 
detection limits of autoanalyzer methods. 

45



Table 2.16: Precision of Dissolved inorganic nutrient analyses during 2000 

HOT 
[Nitrate + Nitrite] SRP Silicate 
Mean 
CV 
(%) 
Mean 
SD 
(M) 
N 
Mean 
CV 
(%) 
Mean 
SD 
(M) 
N 
Mean 
CV 
(%) 
Mean 
SD 
(M) 
N 
111 
112 
113 
114 
115 
116 
117 
118 
119 
120 
121 
0.18 
0.21 
0.31 
0.62 
0.25 
0.60 
0.47 
0.34 
0.57 
0.65 
0.36 
0.032 
0.063 
0.068 
0.078 
0.033 
0.135 
0.078 
0.049 
0.057 
0.049 
0.030 
8 
9 
9 
9 
9 
9 
9 
9 
7 
8 
8 
0.39 
0.37 
1.10 
0.30 
1.09 
0.80 
0.36 
0.58 
0.15 
0.17 
0.37 
0.006 
0.010 
0.012 
0.009 
0.031 
0.016 
0.008 
0.013 
0.004 
0.004 
0.008 
9 
11 
11 
11 
11 
11 
12 
11 
10 
11 
10 
0.26 
5.42 
1.61 
3.42 
1.19 
1.16 
3.65 
1.62 
2.99 
0.38 
1.98 
0.274 
0.309 
0.381 
0.184 
0.313 
0.169 
0.341 
0.358 
0.211 
0.274 
0.307 
9 
11 
11 
12 
11 
11 
12 
11 
10 
11 
10 
Mean 0.41 0.061 11 0.52 0.011 11 2.15 0.284 11 

Between 2001 and 2004, the HOT nutrient program underwent substantial changes, 
including switching analysts twice, eventually establishing an analytical nutrient laboratory 
centered around a six-channel Bran Luebbe Autoanalyzer III. In an effort to continue to provide 
high-quality nutrient data to the scientific community during this transition period, we made the 
decision to ship nutrient samples to Oregon State University for nutrient analyses. The decision 
to send samples to OSU was reached after a blind nutrient analyses comparison was conducted 
among several oceanographic analytical laboratories (including UW, SIO, OSU and UH). Each 
laboratory received triplicate nutrient samples collected at 4 depths (750, 1200, 2200 and 4200 
m) on HOT-163. Using our historical nutrient data as reference, we compared analyses of 
NO2+NO3, and PO4 by these laboratories; analyses conducted by OSU were within our historical 
nutrient concentration climatology. As a result, samples from >200 m depth from HOT 127-166 
(Jun 2001 to December 2004) were shipped to OSU for analyses. 

The OSU nutrient facility uses an AutoAnalyzer II manifold with 5 cm flow cell for PO4 
analyses, and an Alpkem RFA 300 system for analyses of NO2+NO3. 

46



47 
80 
90 
100 
110 
120 
130 
140 
150 
160 
89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 
Dissolved Oxygen (mol kg-1) 
HOT 2-166 (B - 27.782, R - 27.758, G - 27.675) 
34 
35 
36 
37 
38 
39 
40 
41 
42 
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 
Dissolved Nitrate & Nitrite (mol kg-1)
HOT 2-123 (B - 27.782, R - 27.758, G - 27.675) 
Figure 2.4: Concentrations at potential density horizons of 27.782, 27.758 and 27.675 (approx. 
4000m, 3000m and 2000m) at Station ALOHA. The dashed lines indicate the mean while the 
dotted lines show the upper and lower confidence limits. [Upper panel] Dissolved oxygen. 
[Lower panel] nitrate + nitrite. 

48 
2.4 
2.5 
2.6 
2.7 
2.8 
2.9 
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 
Soluble Reactive Phosphorus (mol kg-1) 
HOT 2-123 (B - 27.782, R - 27.758, G - 27.675) 
144 
146 
148 
150 
152 
154 
156 
158 
160 
162 
164 
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 
Dissolved Silicate (mol kg-1) 
HOT 2-123 (B - 27.782, R - 27.758, G - 27.675) 
Figure 2.5: Concentrations at potential density horizons of 27.782, 27.758 and 27.675 (approx. 
4000m, 3000m and 2000m) at Station ALOHA. [Upper panel] Soluble reactive phosphorus. 
[Lower panel] Silicate. 

2.5.3.2 High Sensitivity Methods 
The chemiluminescent method of Cox (1980) as modified for seawater by Garside (1982) 
was used to determine the [nitrate+nitrite] content of near surface (0-200 m interval) water 
samples. The limit of detection for [nitrate+nitrite] was approximately 2 nM with a precision 
and accuracy of 1 nM (Dore et al., 1996). 

Low level soluble reactive phosphorus (SRP) concentrations in the euphotic zone were 
determined according to the magnesium induced coprecipitation (MAGIC) method of Karl and 
Tien (1992). Typical precision estimates for triplicate determinations of SRP are from 1-3 % 
with a detection limit of 2 nM. The MAGIC SRP measurement is also corrected for arsenate 
interference of the molybdenum blue colorimetric procedure (Johnson 1971), unlike the standard 
autoanalytical method. 

2.5.4 Dissolved Organic Matter 
2.5.4.1 Dissolved Organic Carbon 
Dissolved organic carbon (DOC) was determined by the high temperature catalytic 
oxidation method using a Shimadzu Total Organic Carbon Analyzer. Prior to HOT-125 (March 
2001) TOC concentrations had been measured on a commercially available MQ model 1001 
TOC analyzer equipped with a LICOR infrared detector. Beginning in 1997, certified TOC 
reference materials were obtained from J. Sharp (University of Delaware) and D. Hansell 
(University of Miami) and run each time TOC concentrations were analyzed. UV-oxidation 
distilled water is used to determine the instrument blank. The average precisions during 2004 
from duplicate TOC analyses are given in Table 2.17. 

Table 2.17: Precision of Dissolved organic carbon analyses during 2004 

HOT 
DOC 
Mean 
CV 
(%) 
Mean 
SD 
(M) 
N 
155 
156 
157 
158 
159 
160 
161 
162 
163 
164 
165 
166 
3.1 
3.2 
3.1 
3.0 
2.5 
1.6 
2.7 
1.5 
0.5 
3.4 
3.4 
2.3 
1.14 
1.22 
1.37 
1.15 
0.93 
0.57 
1.00 
0.59 
0.17 
1.30 
1.26 
0.84 
4 
4 
5 
4 
4 
4 
3 
3 
4 
4 
4 
4 
Mean 2.5 0.96 12 

49



2.5.4.2 Dissolved Organic Nitrogen and Phosphorus 
Dissolved organic nitrogen (DON) was calculated as the difference between total 
dissolved fixed nitrogen (TDN) and [nitrate+nitrite] concentrations. DON by this definition also 
includes ammonium, however, ammonium concentrations in these waters are below the detection 
limit of standard nutrient analyses (~50 nM). Dissolved organic phosphorus (DOP) was 
calculated as the difference between total dissolved phosphorus (TDP) and SRP concentrations. 
DOP, by this definition includes inorganic polyphosphates. TDN and TDP were determined by 
the UV oxidation method as described in Tupas et al. (1997). The average precisions during 
2000 from duplicate analyses are presented in Table 2.18. 

Table 2.18: Precision of Dissolved organic nitrogen and phosphorus analyses during 2000 

HOT 
DON DOP 
Mean 
CV 
Mean 
SD N 
Mean 
CV 
Mean 
SD N 
(%) (M) (%) (M) 
111 2.4 0.03 2 7.1 0.014 1 
112 4.4 0.10 5 16.3 0.018 4 
113 3.4 0.16 5 14.4 0.011 4 
114 6.7 0.20 5 21.3 0.012 4 
115 8.1 0.33 5 37.1 0.035 4 
116 9.1 0.27 5 30.4 0.034 4 
117 10.1 0.34 5 4.2 0.007 3 
118 6.1 0.58 5 16.0 0.012 4 
119 4.8 0.17 6 8.6 0.011 4 
120 3.5 0.11 6 12.2 0.008 6 
121 9.7 0.55 6 15.3 0.051 5 
Mean 6.2 0.26 11 16.6 0.019 11 

2.5.5 Particulate Bioelements 
2.5.5.1 Particulate Carbon and Nitrogen 
Samples for elemental analyses of Particulate carbon (PC) and nitrogen (PN) were 
prefiltered through 202 m Nitex mesh to remove large zooplankton and collected onto 
combusted 25 mm GF/F glass fiber filters. They were analyzed using a Carla Erba NC 2500 
Elemental Analyzer with a Finnigan MAT ConFlo II coupler and a Finnigan MAT DeltaS mass 
spectrometer. The average precisions during 2004 determined from duplicate analyses are 
presented in Table 2.19. 

50



Table 2.19: Precision of Particulate carbon and nitrogen analyses during 2004 

HOT 
PC PN 
Mean 
CV 
(%) 
Mean 
SD 
(g l-1) 
N 
Mean 
CV 
(%) 
Mean 
SD 
(g l-1) 
N 
155 
156 
157 
158 
159 
160 
162 
163 
164 
165 
166 
6.8 
8.9 
13.0 
5.4 
4.4 
1.4 
3.4 
2.0 
7.2 
12.4 
15.0 
1.432 
1.414 
2.415 
1.446 
1.186 
0.339 
0.721 
0.484 
0.993 
1.782 
2.128 
2 
2 
2 
2 
2 
2 
1 
2 
2 
1 
2 
18.4 
7.7 
2.1 
7.7 
17.5 
3.8 
3.6 
2.7 
3.4 
2.0 
6.4 
0.585 
0.262 
0.069 
0.380 
1.066 
0.175 
0.124 
0.102 
0.110 
0.043 
0.269 
2 
2 
2 
2 
2 
2 
1 
2 
2 
1 
2 
Mean 5.8 1.159 12 7.4 0.319 12 

2.5.5.2 Particulate Phosphorus 

Samples for elemental analyses of Particulate phosphorus were prefiltered through 202 
m Nitex mesh to remove large zooplankton and collected onto combusted, acid washed 25 mm 
GF/F glass fiber filters. Samples were analyzed using high temperature ashing followed by acid 
hydrolysis and subsequent determination of the liberated orthophosphate by colorimetry. These 
procedures are detailed in Karl et al. (1991). The average precisions during 2004 determined 
from duplicate analyses are presented in Table 2.20. 

Table 2.20: Precision of Particulate phosphorus analyses during 2004 

HOT 
PP 
Mean 
CV 
(%) 
Mean 
SD 
(g l-1) 
N 
155 
156 
157 
158 
159 
160 
162 
163 
164 
165 
166 
1.4 
2.9 
32.9 
18.9 
23.7 
7.8 
9.9 
12.0 
17.0 
27.0 
41.4 
0.004 
0.009 
0.124 
0.071 
0.071 
0.021 
0.032 
0.035 
0.046 
0.092 
0.106 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
Mean 17.7 0.056 12 

51



2.5.5.3 Particulate Biogenic Silica 
Samples for elemental analyses of Particulate biogenic silica were collected into 4L 
polyethylene carboys; filtered through 47 mm polycarbonate filter holders; onto 47 mm 
polycarbonate, membrane filters; and placed into 50 ml polypropylene centrifuge tubes. Time 
course subsamples (1.5, 3, 4.5, 6.5 and 24 hours) were measured colorimetrically to distinguish 
Lithogenic-Si from Biogenic-Si (DeMaster, 1981). The average precisions during 2004 
determined from duplicate analyses are presented in Table 2.21. 

Table 2.21: Precision of Particulate biogenic silica analyses during 2004 

HOT 
PSi 
Mean 
CV 
(%) 
Mean 
SD 
(nmol l-1) 
N 
155 
156 
157 
158 
159 
160 
161 
162 
163 
164 
165 
166 
13.6 
10.9 
9.0 
37.0 
16.5 
15.8 
28.1 
27.9 
19.1 
18.7 
14.6 
5.0 
2.924 
1.340 
1.754 
7.669 
3.447 
3.189 
7.283 
4.967 
4.384 
3.405 
2.896 
0.831 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
Mean 18.0 3.674 12 

2.5.6 Pigments 
2.5.6.1 Standard Fluorometric Method 
Samples for chlorophyll a (chl a) and pheopigments were collected onto 25 mm GF/F 
glass fiber filters and measured fluorometrically on a Turner Designs Model 10-AU fluorometer 
with 100% acetone as the solvent using standard techniques (Strickland and Parsons 1972). The 
average precisions during 2004 determined from triplicate analyses are presented in Table 2.22. 

2.5.6.2 High Performance Liquid Chromatography 
Chlorophyll a and photosynthetic accessory pigments were also measured by high 
performance liquid chromatography (HPLC) according to Wright et al. (1991). The response 
factors and retention times yielded by this method during 2004 are presented in Table 2.23. 
Figure 2.6 shows the relationship between chlorophyll a measured by fluorometry and 
chlorophyll a measured by HPLC during 2004. 

52



Table 2.22: Precision of Fluorometric Chlorophyll a and Pheopigment analyses during 2004 

HOT 
Chlorophyll a Pheopigments 
Mean CV 
(%) 
Mean SD 
(g l-1) N Mean CV 
(%) 
Mean SD 
(g l-1) N 
155 
156 
157 
158 
159 
160 
161 
162 
163 
164 
165 
166 
1.7 
3.6 
7.2 
4.4 
4.6 
4.3 
7.9 
2.2 
3.9 
6.2 
6.1 
6.7 
0.002 
0.003 
0.011 
0.005 
0.004 
0.003 
0.018 
0.002 
0.003 
0.004 
0.005 
0.003 
6 
6 
6 
6 
6 
6 
5 
6 
5 
6 
6 
4 
5.1 
9.5 
14.8 
5.4 
7.4 
5.8 
15.3 
4.8 
4.0 
3.0 
10.5 
4.0 
0.012 
0.007 
0.022 
0.013 
0.013 
0.010 
0.052 
0.007 
0.010 
0.007 
0.015 
0.004 
6 
6 
6 
6 
6 
6 
5 
6 
5 
6 
6 
4 
Mean 4.9 0.005 12 7.5 0.014 12 

Table 2.23: 2004 HPLC Pigment analysis Response factors and Retention times 

Pigment RFa RTb 
Chlorophyll c & Mg 3,8DcPeridinin 
19'-Butanoyloxyfucoxanthin 
Fucoxanthin 
19'-Hexanoyloxyfucoxanthin 
Violaxanthin 
Diadinoxanthin 
Alloxanthin 
Lutein 
Zeaxanthin 
Monovinyl Chlorophyll b 
Monovinyl Chlorophyll a 
Divinyl Chlorophyll a 
a-Carotene 
-Carotene 
0.301 
0.697 
0.561 
0.481 
0.608 
0.323 
0.386 
0.415 
0.375 
0.449 
1.264 
0.860 
0.621 
0.456 
0.434 
0.381 
0.403 
0.443 
0.477 
0.590 
0.663 
0.732 
0.806 
0.824 
0.931 
1.000 
1.000 
1.173 
1.182 

aRF - Response Factor (ng l-1 pigment per unit absorbance peak area at 436 nm). 
bRT - Retention Time (minutes, relative to chlorophyll a) 
cChlorophyll c = (c1 + c2 + c3), Mg 3,8D = Mg 3,8 divinyl pheoporphyrin a5


monomethyl ester. 

53 


0 
0.05 
0.1 
0.15 
0.2 
0.25 
0.3 
0.35 
0.4 
Chla F ( g l -1 ) 
HOT 155-166 (Fchl = Hchl*0.71 + 0.0077, R2=0.95, N=116) 

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 
Chla HPLC ( g l-1) 

Figure 2.6: Chlorophyll a measured by fluorometry (Chla F) versus chlorophyll a measured by 
HPLC (Chla HPLC) for all data collected in 2004. The black line shows the 1:1 x-y relationship 
while the red line is a model II linear regression analysis of the data set. The regression equation 
is at the top of the figure. 

54



2.5.6.3 Chlorophyll a, b, c 
In mid-2000 we started measuring chlorophyll a, b, & c on a Turner Designs TD-700. 
Samples were filtered onto 25 mm GF/F glass fiber filters and put into 100% acetone similar to 
the standard fluorometric method (Section 2.5.6.1). Samples were analyzed using the wavelength 
filters shown in Table 2.24. The average precisions during 2004 determined from triplicate 
analyses are presented in Table 2.25. Figure 2.7 shows the relationship between chlorophyll a 
measured using the TD-700 & chlorophyll a measured using the 10-AU as well as chlorophyll a, 
b & c measured by HPLC during 2004. 

Table 2.24: Wavelength filters used for TD-700 Chlorophyll analyses 

Chlorophyll 

Ex 

Em 

a 

436 

680 

b 

480 

650 

c 

450 

630 

Table 2.25: Precision of TD-700 Chlorophyll analyses during 2004 

HOT 
Chlorophyll a Chlorophyll b Chlorophyll c 
Mean 
CV 
Mean 
SD N 
Mean 
CV 
Mean 
SD N 
Mean 
CV 
Mean 
SD N 
(%) (g l-1) (%) (g l-1) (%) (g l-1) 
155 2.6 0.004 6 10.2 0.007 6 6.0 0.002 6 
156 2.0 0.003 6 6.4 0.003 6 8.3 0.001 6 
157 7.7 0.013 6 13.1 0.007 6 7.1 0.002 6 
158 3.2 0.006 6 18.8 0.009 6 6.2 0.001 6 
159 3.6 0.005 6 7.9 0.004 6 4.0 0.001 6 
160 2.2 0.003 6 7.6 0.004 6 3.4 0.001 6 
161 8.8 0.023 4 19.5 0.019 4 9.2 0.004 4 
162 1.2 0.002 6 6.7 0.004 6 2.7 0.001 6 
163 1.8 0.003 5 9.8 0.005 5 3.7 0.001 5 
Mean 3.7 0.007 9 11.1 0.007 9 5.6 0.002 9 

2.5.6.4 Underway Surface Chloropigment 
Continuous in vivo chloropigment (fluorescence) from surface seawater was measured 
using a Turner Designs Model 10-AU fluorometer installed on the ships seawater intake system. 
The underway measurements were calibrated by taking discrete samples from the outflow of the 
fluorometer and extracting the pigments according to the standard fluorometric method (Section 
2.5.6.1). 

55 


C = A * 0.92 + -0.01, R2 = 0.96 C = A * 1.32 + -0.03, R2 = 0.95 

0 
0.1 
0.2 
0.3 
0.4 
10-AU Chl a ( g l -1 ) 
0 
0.1 
0.2 
0.3 
0.4 
HPLC Chl a ( g l-1 ) 
0 0.1 0.2 0.3 0.4 0 0.1 0.2 0.3 0.4 
TD-700 Chl a ( g l-1) TD-700 Chl a ( g l-1) 
C = A * 1.53 + -0.01, R2 = 0.90 C = A * 1.60 + -0.01, R2 = 0.92 

0.3 

0.1 

0 0.1 0.2 0.3 
0 0.02 0.04 0.06 0.08 0.1 
HPLC Chl b ( g l -1) 

HPLC Chl c ( g l -1)

0.08 

0.06 

0.04 

0.02 

0.2 

0.1 

0 

0 

TD-700 Chl b ( g l-1) TD-700 Chl c ( g l-1) 

Figure 2.7: Chlorophyll measured using the TD-700 versus chlorophyll measured using the 10AU 
and by HPLC for all data collected in 2004. The black line shows the 1:1 x-y relationship 
while the red line is a model II linear regression analysis of the data set. The regression equation 
is at the top of each figure. 

56



2.5.6.5 Phycoerythrin 
Unlike the HPLC pigments which are oil soluble, phycoerythrin is a water soluble 
pigment which can be used as a marker for cyanobacteria such as Trichodesmium spp. Samples 
were size fractionated through 10m & 5m nylon membrane filters, 1L of the filtrate collected, 
then poured through a 0.4m poly-carbonate filter. Samples were analyzed using a Turner 
Designs TD-700 with 544 nm (Ex) & 577 nm (Em) wavelength filters, and the fluorescence 
obtained. Phycoerythrin was then calculated via the formula: 

PE = (fluor  B) / M 

where M & B are the slope and intercept respectively of the regression curve obtained by using 
our pure phycoerythrin stock. 

2.5.7 Adenosine 5-triphosphate 
The amount of living microbial biomass in the water column was determined by the 
measurement of adenosine 5'-triphosphate (ATP) concentrations. Seawater samples were filtered 
through 47 mm GF/F glass fiber filters to collect particulate material and the filters placed in 
boiling Tris-buffer for ATP extraction. ATP concentrations were determined using the firefly 
bioluminescence technique described by Karl and Holm-Hansen (1978). 

The average precisions of Particulate ATP determinations during 2004 determined from 
triplicate analyses are presented in Table 2.26. 

Table 2.26: Precision of Particulate ATP analyses during 2004 

HOT 
Particulate ATP 
Mean CV 
(%) 
Mean SD 
(ng l-1) N 
155 
156 
157 
158 
159 
160 
161 
162 
163 
164 
165 
8.4 
10.8 
19.6 
9.9 
13.5 
13.4 
12.6 
20.0 
6.8 
19.4 
17.5 
1.425 
1.522 
4.707 
1.521 
1.543 
1.827 
2.832 
3.800 
1.380 
2.307 
3.028 
9 
9 
8 
9 
9 
9 
7 
9 
9 
8 
9 
166 14.7 2.889 9 
Mean 13.9 2.398 12 

57



2.6 Biogeochemical Rate Measurements 
2.6.1 Primary Production 
Photosynthetic production of organic matter was measured by the 14C tracer method. All 
incubations from 1990 through mid-2000 were conducted in situ at eight depths (5, 25, 45, 75, 
100, 125, 150 & 175m) over one daylight period using a free-drifting array as described by Winn 
et al. (1991). Starting HOT-119 (October 2000), we collected samples from only the upper six 
depths & modeled the lower two depths based on the monthly climatology. Some incubations 
during 1988-1990 were carried out in situ, and some on deck under simulated in situ light and 
temperature conditions. Integrated carbon assimilation rates were calculated using the trapezoid 
rule with the shallowest value extended to 0 m and the deepest extrapolated to a value of zero at 
200 m. 

2.6.2 Particle Flux 
Particle flux was measured at a standard reference depth of 150 m using multiple 
cylindrical particle interceptor traps deployed on a free-floating array for approximately 60 h 
during each cruise. Sediment trap design and collection methods are described in Winn et al. 
(1991). Samples were analyzed for particulate C, N, P and Si as described in Section 2.5.5 
above. Typically six traps are analyzed for PC and PN, three for PP, and another three traps for 
PSi. 

2.7 Optical Measurements 
2.7.1 Solar Irradiance 
Incident irradiance (400-700 nm wavelength band) at the sea surface was measured on 
each HOT cruise with a LI-COR LI-1000 data logger and cosine collector. The instrument 
recorded data from the time the ship departed Snug Harbor until its return. 

2.7.2 Downwelling Irradiance and Upwelling Radiance 
Vertical profiles of upwelling radiance and downwelling irradiance were made using a 
Biospherical PRR-600 Profiling Reflectance Radiometer. Surface irradiance was collected using 
a sister instrument (PRR-610). These instruments measures downwelling irradiance (Ed) and 
upwelling radiance (Lu) as well as surface irradiance (Es) from a deck unit on 7 wavelength 
channels (Table 2.27). The radiance channels comply with the SeaWIFS satellite optical 
parameters. The instrument is lowered by hand and depending on the subsurface currents, is 
deployed to a depth between 125 and 175 meters. 

58



Table 2.27: PRR-600 and PRR-610 Wavelengths 

Channel Downwelling 
(Ed) 
Upwelling 
(Lu) 
Surface 
(Es) 
1 412 412 412 
2 443 443 443 
3 490 490 490 
4 510 510 510 
5 555 555 555 
6 665 665 665 
7 PAR 683 PAR 

2.7.3 Tethered Spectral Radiometer Buoy (TSRB) 
The TSRB was used to make continuous measurements of downwelling irradiance just 
above the sea surface, upwelling radiance just below the sea surface, and sea surface temperature 
at the sea surface. The instrument measures downwelling irradiance at 489nm and upwelling 
radiance at 410, 444, 489, 511, 553, 668 and 684nm. All wavelengths except the 684nm 
waveband have bandpasses of approximately 20nm. The 684nm waveband has a bandpass of 
10nm. The sampling frequency is 1 Hz. 

During HOT-151 (August 2003), the TSRB got tangled in the ships aft propeller. Due to 
marginal sea conditions, the captain deemed it unsafe to send a diver to untangle the buoy. The 
wire was cut in the hope that the buoy would untangle itself and float to the surface. It did not. 
At present, we have TSRB data from HOT-89 through HOT-150 (January 1998  July 2003). 

2.7.4 Inherent Optical Properties (IOPs): Absorption and Beam Attenuation 
Profiles of absorption (a(.)) and beam attenuation (c(.)) were made using a WET Labs 
AC-9. The AC-9 simultaneously determined the spectral attenuation and spectral absorption of 
water at 412, 440, 488, 510, 532, 555, 650, 676 and 715nm. Each of these wavebands have 
bandpasses of approximately 10 nm. The sampling frequency is approximately 6 Hz. 


The AC-9 was part of an instrument package that also included a Sea-Bird CTD, WET 
Labs WetStar fluorometer and a Chelsea Fast Repetition Rate Fluorometer (FRRF). The 
instrument was oriented horizontally and lowered at a more-or-less constant speed of 10 m min-1 
to a bottom depth of approximately 250 m (justification given in Section 2.7.5). At least 2 back-
to-back profiles were normally taken, one using a 0.2 m cartridge filter and one without. This 
allowed the spectral absorption and attenuation coefficient of both the total & dissolved matter to 
be determined. The particulate absorption and attenuation components were derived by 
subtracting the dissolved from the total component. The scattering of particles was estimated by 
subtracting the absorption from the attenuation particle spectrum. 

59



2.7.5 Fast Repetition Rate Fluorometry (FRRF) 
Day and night time FRRF profiles were made using a Chelsea FASTtracka Dynamic 
Photosynthetic Fluorometer. The FRRF was part of an instrument package that also included a 
Sea-Bird CTD, WET Labs WETStar fluorometer and a WET Labs AC-9. The instrument was 
oriented horizontally and lowered at a more-or-less constant speed of 10 m min-1 to a bottom 
depth of approximately 250 m. This speed was empirically determined to better resolve 
fluorescence response of small scale (~ 0.5m) photoautotrophic assemblages and to allow 
enough time for the gain switch of the instrument without losing significant vertical resolution 
(Corno et. al. 2005). The sampling protocol of the FRRF was set to an acquisition sequence of 
100 saturation flashes, 20 relaxation flashes and 10 m sec-1 sleep time between acquisitions. The 
flash duration was of 0.65  sec (4 instrument units). This sampling protocol was found to better 
characterize the fluorescence response (i.e. saturation curve fitting) of this specific oceanic 
waters in preliminary tests (G. Corno unpublished data). Depth and in situ irradiance (PAR) were 
also logged with each profile. 

2.8 Microbial Community Structure 
Analysis of microbial numbers was made using an EPICS 753 flow cytometer (Coulter 
Electronics Corporation, Hialeah, FL, USA) which has been upgraded with a Cicero Data 
Acquisition System (Cytomation Inc., Boulder, Colorado). Prior to analysis by flow cytometry, 
samples were prepared using standard protocols (Monger & Landry 1993; Campbell et al., 
1994). Enumeration efficiency was tracked using fluorescent beads. Cyanobacteria of the 
genera Prochlorococcus and Synechococcus were separately enumerated, as well as nonpigmented 
bacteria/archaea and pigmented eukaryotes. 

2.9 Zooplankton Community Structure 
2.9.1 Mesozooplankton Collection 
Samples for the quantification of mesozooplankton were collected using a 1 m2 plankton 
net with a 202 m Nitex mesh. The net is towed obliquely at a speed of 1.0-1.5 knots while 
deploying and retrieving the tow line at a constant speed (about 20 meters min-1; total line out = 
200 meters; 20 minute tow duration; average depth of tow  175 meters). Three midnight 
(between 2200-0200 local time) and three mid-day (between 1000-1400 local time) tows are 
conducted on each cruise. This sampling scheme allows maximal collection of vertical migrants 
during the night and minimal collection of vertical migrants during the day. 

2.9.2 Sample Processing 
Immediately after the net tows, contents of the collecting buckets (cod ends) are divided 
using a Folsom splitter. One-half of each tow is preserved in 4% buffered formaldehyde, with 2 
mg l-1 strontium sulfate added to prevent acantharians from dissolving. Approximately one-
fourth of each tow, depending on sample density, is further size-fractionated through nested 

60



screens of 5, 2, 1, 0.5 and 0.2 mm Nitex mesh. Each size fraction is filtered onto a preweighed 

0.2 m Nitex filter, rinsed with isotonic ammonium formate to remove salts, sucked dry under 
low vacuum, and flash frozen in liquid nitrogen. In the lab, frozen samples are defrosted at room 
temperature and weighed wet (moist) on an analytical balance. After a wet weight is obtained 
random subsamples of the zooplankton mass are removed and set aside for enumeration, and the 
remaining sample is dried at 60 C. Dry samples are reweighed to obtain a total sample dry 
weight [total sample dry weight = measured dry weight/fraction of total wet weight dried]. The 
dry samples are analyzed for carbon and nitrogen. 
61



3.0 CRUISE SUMMARIES 
The cruise summaries presented here give an overview of the activities conducted during 
the 2004 HOT cruises. The official Chief Scientist's reports can be found on the HOT-BEACH 
(hahana.soest.hawaii.edu/hot/cruises.html) and HOT-PO web pages. 

3.1 HOT-155 
Chief Scientist: T. GREGORY 
R/V Ka'imikai-o-Kanaloa 
20-24 January 2004 

All operations at Stations ALOHA, Kahe and Kaena Pt. were conducted as planned. 
Thirteen 1000 m and two 4800 m CTD casts were obtained at Station ALOHA. One 2500 m 
cast was obtained at Station Kaena Pt. All free-floating arrays were deployed and recovered 
without incident. M. Simmons successfully completed five plankton net tows. The net ripped on 
the final tow, possibly due to marginal wind and sea conditions. Weather conditions were 
favorable throughout the cruise except for a squall with 50 knot gusts which delayed the second 
deep cast. The ADCP ran without interruption throughout the cruise, as well as the fluorometer, 
thermosalinograph and the ship's anemometer. We arrived back at Snug Harbor on Jan. 24 at 
around 0730. A complete off-load took place immediately. 

3.2 HOT-156 
Chief Scientist: D. SADLER 
R/V Ka'imikai-o-Kanaloa 
23-27 February 2004 

All operations at all stations were conducted as planned. Thirteen 1000m and two 4800 m 
CTD casts were obtained at Station ALOHA. A 1000 m cast was obtained at Station Kahe. A 
2500 m CTD cast was completed at Kaena Point. Also, three PRR casts were performed: one at 
Station Kahe and two at Station ALOHA. C. Sheridan successfully completed six plankton net 
tows. The PRR and AC9/FRRf were deployed as planned. The ADCP ran without interruption 
throughout the cruise, as well as the fluorometer, thermosalinograph and the ship's anemometer. 
Weather during the cruise was influenced by some systems to the South, causing mostly cloudy 
conditions with southerly winds. A strong NNE current during the cruise carried the primary 
production and sediment trap arrays out of the station circle by 9 nm and 22 nm, respectively. 
We arrived back at Snug Harbor on February 27 at 0818. A complete off-load took place 
immediately. 

62



3.3 HOT-157 
Chief Scientist: F. SANTIAGO-MANDUJANO 
R/V Kilo Moana 
18-22 March 2004 

Operations were conducted as planned the first three days of the cruise, with delays in 
CTD operations caused by the increasingly rough weather. The CTD wire developed kinks 
during three casts and required retermination. The light casts planned for the last day of the 
cruise were cancelled because the ship had to return to Honolulu harbor to disembark one of the 
cruise members (Tom Gregory) who had to attend a family emergency. The two Sea-Bird casts 
planned for the last day were combined into one cast, which was conducted SW of Honolulu. 
Twelve 1000-m CTD casts and one deep cast (~4740 m) were conducted at Station ALOHA. 
Two 1000-m CTD casts were conducted at Station Kahe, one of them was for Sea-Bird. One 
deep CTD cast was conducted by Sea-Bird personnel SW of Honolulu. The array of floating 
sediment traps and the primary productivity incubation array were deployed, and recovered 
without incidents despite the rough weather. Both arrays drifted east. C. Sheridan completed 
successfully 6 plankton net tows. The PRR and AC9/FRRf were deployed as planned, except 
during the last day of the cruise. The ADCP and thermosalinograph ran without interruption 
throughout the cruise, as well as the fluorometer, and the ship's two anemometers. Winds were 
from the north at 15-20 kt early in the cruise, increasing to more than 30 kt the last day, changing 
direction to NE. The swell at ALOHA was about 6-8 ft the second day of the cruise, increasing 
to more than 15 ft the last day at ALOHA. Scattered showers were present during the cruise. We 
arrived back at Snug Harbor on March 22 at 0730. Full off-load took place immediately. 

3.4 HOT-158 
Chief Scientist: D. SADLER 
R/V Ka'imikai-o-Kanaloa 
19-23 April 2004 

All operations at all stations were conducted as planned. Thirteen 1000 m, two 4800 m 
and one 100 m CTD casts were obtained at Station ALOHA. A 1000 m cast was obtained at 
Station Kahe. A 2500 m CTD cast was completed at Station Kaena. Also, three PRR casts were 
performed: one at Station Kahe and two at Station ALOHA. M. Simmons successfully 
completed six plankton net tows. The PRR and AC9/FRRf were deployed as planned. The 
ADCP ran without interruption throughout the cruise, as well as the fluorometer, 
thermosalinograph and the ship's anemometer. Weather during the cruise was mostly fair with 
light trade winds and occasional light rain. We returned to Snug Harbor on April 23 at 0737. A 
complete off-load took place immediately. 

63



3.5 HOT-159 
Chief Scientist: T. GREGORY 
R/V Ka'imikai-o-Kanaloa 
17-21 May 2004 

All operations at Stations ALOHA, Kahe and Kaena were conducted as planned. One 
1000 m cast was performed at Station Kahe. Thirteen 1000 m and two 4740 m CTD casts were 
obtained at Station ALOHA. One 2500 m cast was obtained at Station Kaena. All free-floating 
arrays were deployed and recovered without incident. C. Sheridan successfully completed six 
plankton net tows. Weather conditions were favorable throughout the cruise. The ADCP ran 
without interruption throughout the cruise, as well as the fluorometer, thermosalinograph and the 
ship's anemometer. We arrived back at Snug Harbor on May 21 at around 0730. A partial off-
load took place immediately. 

3.6 HOT-160 
Chief Scientist: T. GREGORY 
R/V Ka'imikai-o-Kanaloa 
14-18 June 2004 

All operations at Stations ALOHA, Kahe and Kaena were conducted as planned. One 
1000 m cast was obtained at Station Kahe. Fourteen 1000 m, two 4740 m, and one 200 m CTD 
casts were obtained at Station ALOHA. One 2500 m cast was obtained at Station Kaena. All 
free-floating arrays were deployed and recovered without incident. M. Simmons successfully 
completed six plankton net tows. Weather conditions were favorable throughout the cruise. The 
ADCP ran without interruption throughout the cruise, as well as the fluorometer, 
thermosalinograph and the ship's anemometer. We arrived back at Snug Harbor on June 18 at 
around 0730. A full off-load took place immediately. 

3.7 HOT-161 
Chief Scientist: F. SANTIAGO-MANDUJANO 
R/V Ka'imikai-o-Kanaloa 
12-14 July 2004 

The cruise was cut short to less than 2.5 days because one of the ship's generators failed 
during transit to ALOHA station. The ship returned to Honolulu after conducting operations at 
ALOHA for 10 hours. Operations at Kahe station were conducted as planned. One 1000-m CTD 
cast was conducted at this station. Due to the ship's generator problem, operations at ALOHA 
were reduced to a minimum. One deep cast (~4740 m), and four shallow casts between 175 and 
700-m were conducted at Station ALOHA. Neither the sediment traps nor the primary 
productivity array were deployed. The plankton net tows were not deployed either. The PRR was 
deployed at Kahe Station on July 12, and at ALOHA station on July 13. The ADCP ran without 
interruption throughout the cruise, as well as the thermosalinograph, fluorometer, and the ship's 

64



two anemometers. Winds were easterlies at 20 kt, and sea state 4. We arrived back at Snug 
Harbor on July 14 at 1400. Full off-load took place on July 15. 

3.8 HOT-162 
Chief Scientist: D. SADLER 
R/V Ka'imikai-o-Kanaloa 
14-18 August 2004 

All planned operations were completed with two exceptions. A medical emergency 
resulted in cancellation of the cast at Station Kaena and one optical cast. Nine 1000 m, two 4800 
m and one 700 m CTD casts were obtained at Station ALOHA. A 1000 m cast was obtained at 
Station Kahe. Four 200 m casts were completed near the buoys. Also, two PRR casts were 
performed: one at Station Kahe and one at Station ALOHA. C. Sheridan and M. Miller 
successfully completed six plankton net tows. The AC9/FRRf was deployed twice at Station 
ALOHA. The evening cast was cancelled due to the emergency transit to Haleiwa. The ADCP 
ran without interruption throughout the cruise, as well as the fluorometer, thermosalinograph and 
the ship's anemometer. Weather during the cruise was mostly fair with trade winds and 
occasional light rain. The last day of the cruise brought light winds and near calm sea conditions. 
We returned to Snug Harbor on August 18 at 1225. A complete off-load took place immediately. 
The 36 hour CTD burst sampling was not completed due to the medical emergency. 

3.9 HOT-163 
Chief Scientist: F. SANTIAGO-MANDUJANO 
R/V Ka'imikai-o-Kanaloa 
27 September - 1 October 2004 

Operations during the cruise were conducted as planned, with minor delays in the 
schedule during the first 4 CTD casts at ALOHA Sta. One 1000-m CTD cast was conducted at 
Kahe station. Fifteen 1000-m CTD casts and two deep casts (~4740 m) were conducted at 
Station ALOHA. Two 200-m CTD cast were conducted near the ORS and MOSEAN moorings 
(Stations 50 and 51) respectively. One deep cast (~2400 m) was conducted at Station Kaena. The 
array of floating sediment traps and the primary productivity incubation array were deployed and 
recovered without incidents. Both arrays drifted west. C. Hannides completed successfully 6 
plankton net tows. The PRR and AC9/FRRf were deployed as planned. The ADCP ran without 
interruption throughout the cruise, as well as the thermosalinograph, fluorometer, and the ship's 
two anemometers. Winds were easterlies of about 14 kt early in the cruise, increasing to 17 kt 
later in the cruise. A northward swell of about 7-8 ft persisted during the cruise. We arrived back 
at Snug Harbor on October 1st at 0730. Full off-load took place immediately. 

65



3.10 HOT-164 
Chief Scientist: T. GREGORY 
R/V Ka'imikai-o-Kanaloa 
29 October - 2 November 2004 

Most operations at Stations ALOHA, Kahe and Kaena were conducted as planned. One 
1000 m cast was obtained at Station Kahe. Thirteen 1000 m, and two 4800 m CTD casts were 
obtained at Station ALOHA. One 200 m cast was performed at both mooring stations. One 2500 
m cast was obtained at Station Kaena. Both free-floating arrays were deployed and recovered 
without incident. Due to AC9 battery problems, the AC9/FRRf optics package was deployed for 
one nighttime cast and one daytime cast on Nov. 1. M. Simmons successfully completed six 
plankton net tows. Weather conditions did not affect our cruise objectives however we did 
experience rainy weather. The rain was quite heavy at times. The ADCP ran without interruption 
throughout the cruise, as well as the fluorometer, thermosalinograph and the ship's anemometer. 
We arrived back at Snug Harbor on Nov. 2 at around 0800. A full off-load took place 
immediately. 

3.11 HOT-165 
Chief Scientist: F. SANTIAGO-MANDUJANO 
R/V Ka'imikai-o-Kanaloa 
26-30 November 2004 

Operations during the cruise were conducted as planned, with minor delays in the 
schedule for the first two CTD casts at ALOHA Sta. One 1000-m CTD cast was conducted at 
Station Kahe. Thirteen 1000-m CTD casts and two deep casts (~4740 m) were conducted at 
Station ALOHA. One 200-m CTD cast was conducted near the ORS mooring (Station 50). One 
near-bottom cast (~2400 m) was conducted at Station Kaena (Station 6). The array of floating 
sediment traps and the primary productivity incubation array were deployed and recovered 
without incidents. Both arrays drifted northeast. M. Simmons completed successfully 6 plankton 
net tows. The PRR and AC9/FRRf were deployed as planned. The ADCP ran without 
interruption throughout the cruise, as well as the thermosalinograph, and the ship's two 
anemometers. No continuous fluorometer data were collected because the sensor was being 
calibrated at Turner. Winds were easterlies of about 10 kt early in the cruise, increasing to 25 kt 
by the end of the cruise. A swell from NE of up to 10 ft was also present by the end of the cruise. 
We arrived back at Snug Harbor on November 30 at 0800. Full off-load took place immediately. 

66



3.12 HOT-166 
Chief Scientist: T. GREGORY 
R/V Ka'imikai-o-Kanaloa 
18-23 December 2004 

The MOSEAN mooring was successfully deployed. A late arrival to Station ALOHA and 
a longer than expected mooring deployment required some shuffling of operations on Dec. 19. 
Nevertheless, most operations at Stations ALOHA and Kaena were conducted as planned and all 
sampling objectives were met. One 125 m, one 350 m, thirteen 1000 m, and two 4800 m CTD 
casts were obtained at Station ALOHA. One 200 m cast was performed at Station 51 and one 
2500 m cast was obtained at Station Kaena. All optics cast objectives were completed. Both free-
floating arrays were deployed and recovered without incident. C. Hannides successfully 
completed six plankton net tows. Weather conditions were favorable throughout the cruise. The 
ADCP ran without interruption throughout the cruise, as well as the fluorometer, 
thermosalinograph and the ship's anemometer. We arrived back at Snug Harbor on Dec. 23 at 
around 0800. A full off-load took place immediately. 

67



4.0 RESULTS 
4.1 Hydrography 
4.1.1 2004 CTD Profiling Data 
Profiles of temperature, salinity, oxygen and potential density (s.) were obtained from 
data collected at Stations Kahe, ALOHA, and Kaena. The downcast CTD profiles from Station 
ALOHA during 2004 are presented in Figures 6.1.1a to l, together with the results of bottle 
determinations of oxygen and salinity. Stack plots of CTD temperature and salinity profiles for 
all 1000 m casts conducted at Station ALOHA are also presented (Figures 6.1.2a to l). The offset 
between bottle salinities and CTD profiles apparent in some of the cruise's salinity vs. pressure 
plots is due to the mismatch between the downcast CTD profile and the bottle salinities, which 
are taken during the upcast. This salinity mismatch is caused mostly by vertical displacements of 
the density structure and disappears when plotted against potential temperature (lower right 
panel in Figures 6.1.1a to l). In some instances mismatches are caused by freshening of the 
surface water due to rain during the cast. 

Profiles of chloropigment (in vivo fluorescence) are shown in Figures 6.1.3a to l. 
Chloropigment profiles show the chlorophyll maximum at the base of the euphotic zone, 
characteristic of the central North Pacific Ocean. Chloropigment profiles show the influence of 
internal waves when plotted against pressure, but remain relatively constant within a cruise when 
plotted against potential density (s.). However, there is substantial cruise-to-cruise variability in 
both the position and magnitude of the chlorophyll maximum. 

Profiles of the data collected for Stations Kahe and Kaena during 2004 are presented in 
Figures 6.1.4a to l. Station Kaena was not visited during HOT-157, 161, and 162 because of time 
constraints. 

The potential temperature, salinity and oxygen profiles obtained from the deep casts at 
Station ALOHA during 2004 are presented in Figures 6.1.5-7. 

4.1.2 Time-series Hydrography, 1988-2004 
The hydrographic data collected during the first sixteen years of HOT are presented in a 
series of contour plots (Figures 6.1.8-23). These figures show the data collected in 2004 within 
the context of the longer time-series. The CTD data used in these plots are obtained by averaging 
the data collected during the 36-hour period of burst sampling. Therefore, much of the 
variability, which would otherwise be introduced by internal tides, has been removed. Figures 

6.1.8 and 6.1.9 show the contoured time-series for potential temperature and density (s.) in the 
upper 1000 dbar for all HOT cruises through 2004. Seasonal variation in temperature for the 
upper ocean is apparent in the maximum of near-surface temperature of about 26 C and the 
minimum of approximately 23 C. Oscillations in the depth of the 5 C isotherm below 500 dbar 
appear to be relatively large with displacements up to 100 dbar. The main pycnocline is observed 
between 100 and 600 dbar, with a seasonal pycnocline developing between June and December 
in the 50-100 dbar range (Figure 6.1.9). The cruise-to-cruise changes between February and July 
68



1989 in the upper pycnocline illustrate that variability in density is not always well resolved by 
our quasi-monthly sampling. 

Figures 6.1.10-13 show the contoured time-series record for salinity in the upper 1000 
dbar for all HOT cruises through 2004. The plots show both the CTD and bottle results plotted 
against pressure and potential density. Most of the differences between the contoured sections of 
bottle salinity and CTD salinity are due to the coarse distribution of bottle data in the vertical as 
compared to the CTD observations. Some of the bottles in Figure 6.1.13 are plotted at density 
values lower than the indicated sea surface density. This is due to surface density changing from 
cast to cast within each cruise, and even between the downcast and the upcast during a single 
cast. 

Surface salinity is variable from cruise-to-cruise, with no obvious seasonal cycle and 
some substantial interannual variability. Relatively low surface salinities occurred during 1989, 
the early part of 1995, and during 1996. A relative increase in surface salinity that started in the 
late months of 1997 continued throughout 2003, intensifying in the first half of 1999 and 
remaining with high values during the major part of 2000, 2001 and early 2002, showing a 
decrease in mid-2002 and mid-2003, and even more during the second half of 2004, and 
increasing again by the end of 2002, early 2003, late 2003, and early 2004. This increase is also 
present in deeper layers reaching 200 dbar (Figure 6.1.10). The salinity decrease during the 
second half of 2004 reached values comparable to those during 1996. 

The salinity maximum is generally found between 50 and 150 dbar, and within the range 
24-25 s.. A salinity maximum region extends to the sea surface in the later part of 1990, 1993 
and during 1998 throughout the early months of 2002, during late 2002 and early 2003, and 
again in the late part of 2003 and early 2004, as indicated by the 35.2 contour reaching the 
surface. The maximum shows salinities lower than normal in early 1995 and 1996, and 
throughout these two years the values are below 35.2. During 1997 the salinities decrease even 
further, with values below 35.1, to recover rapidly after February 1998 to values prior to 1995. 
The increase continues throughout 2003, reaching record values of up to 35.45 in the first half of 
1999. These salinity anomalies seem to be related to rainfall anomalies in the central North 
Pacific dominated by the El Nio/Southern Oscillation phenomenon and by the Pacific Decadal 
Oscillation (Lukas, 2001). During this period of high salinities in the salinity maximum, brief 
periods of relatively lower salinity are observed during the second half of 1998, 1999, and 2003. 

The maximum value of salinity in the salinity maximum region is subject to short-term 
variations of about 0.1, which is probably due to the proximity of Station ALOHA to the region 
where this water is formed at the sea surface (Tsuchiya, 1968). The variability of this feature is 
itself variable. Throughout 1989 there were extreme variations of a couple of months duration 
with 0.2 amplitude. The variability was much smaller and slower thereafter, except for a few 
months of rapid variation in earlier 1992. 

The salinity minimum is found between 400 and 600 dbar (26.35-26.85 s.). There is no 
obvious seasonal variation in this feature, but there are distinct periods of higher than normal 
minimum salinity in early 1989, in the fall of 1990, in early 1992 and in the summer of 1996. 
These variations are related to the episodic appearance at Station ALOHA of energetic fine 
structure and submesoscale water mass anomalies (Lukas and Chiswell, 1991; Kennan and 

69



Lukas, 1995). The anomalous high salinity centered at 400 dbar in early 2001 was apparently 
caused by the passing of an eddy during HOT-122 (Lukas and Santiago-Mandujano, 2001). This 
caused anomalous values in all the hydrographic variables observed at the ALOHA station. 

Figures 6.1.14 and 6.1.15 show contoured time-series data for oxygen in the upper 1000 
dbar at Station ALOHA. The oxygen data show a strong oxycline between 400 and 625 dbar 
(26.25-27.0 s.), and an oxygen minimum centered near 800 dbar (27.2 s.). Recurrent drops in 
the oxygen concentration can be seen throughout the time-series between 25 and 26.25 s.. These 
features are accompanied by a decrease in salinity and an increase in the nutrient concentration 
(see discussion below). The anomalous low oxygen centered at 400 dbar in early 2001 is due to 
the previously mentioned eddy feature observed during HOT-122. 

The oxygen minimum exhibits some interannual variability, with values less than 30 
mol kg-1 appearing frequently during the time-series. This variability can be seen in a plot of 
the mean oxygen in the intermediate waters spanning the oxygen minimum (27-27.8 s., Figure 
6.1.24). Superimposed on this variability is a general trend towards lower oxygen values from 
1989 throughout 1996, with an increase between 1997 and 2000, followed by a sharp decrease 
during 2001, and reaching record low values during the second half of 2002, and increasing 
sharply during 2003 and 2004 to reach record high values in mid-2004. 

The surface layer shows a seasonality in oxygen concentrations, with highest values in 
the winter. This pattern corresponds roughly to the minimum in surface layer temperature 
(Figure 6.1.8). 

Figures 6.1.16-23 show [nitrate + nitrite], SRP, and silica at Station ALOHA plotted 
against both pressure and potential density. The nitricline is located between about 200 and 600 
dbar (25.75-27 s.; Figures 6.1.16-17). Most of the variations seen in these data are associated 
with vertical displacements of the density structure, and when [nitrate + nitrite] is plotted versus 
potential density, most of the contours are level. Recurrent events with increasing [nitrate + 
nitrite] can be seen throughout the series between 25-26.25 s. (Figure 6.1.17). These events are 
accompanied by a decrease in the oxygen concentration mentioned above (Figure 6.1.15). The 
most obvious events occurred in March-April 1990, January 1992, May 1992, February-March 
1995, early 1996, mid- to late 1997, and July-September 1999. These events can likely be 
attributed to mesoscale features such as eddies. It is possible for eddies to transport water with 
different biogeochemical characteristics from distant sources into the region of Station ALOHA 
(Lukas and Santiago-Mandujano, in prep.). The SRP variability is similar to the [nitrate + nitrite] 
in the upper water column (Figure 6.1.20-21). 

During 1996, the intermediate waters between 27.0-27.8 s. recovered from anomalously 
low [nitrate + nitrite] which was observed during 1995 (Figure 6.1.18). This anomaly is apparent 
in a time series of mean [nitrate + nitrite] between 27.0-27.8 s. (Figure 6.1.24). A decrease in 
[nitrate + nitrite] began in late 1994, with a comparable increase from mid-1995 through early 
1996. The maximum decrease appears to be about 1 mol kg-1 below 27.5 s. where nitrate 
concentrations are about 40 mol kg-1. This decrease appears to be real as it does have coherence 
over time. A precision estimate of 0.3% has been made for [nitrate + nitrite] measurements 
involving the high concentration samples associated with intermediate water (Dore et al., 1995). 
This translates to a precision of roughly 0.12 mol kg-1 for samples with a concentration of 40 

70



mol kg-1. Hence, the 1 mol kg-1 decrease seen during 1995 is well within the precision level 
for the concentrations observed. However, the amount of the decrease could be approaching the 
accuracy limits of [nitrate + nitrite] measurements. This low [nitrate + nitrite] episode is 
accompanied by an increase in oxygen concentration (Figure 6.1.24). 

Intermediate water SRP (between 27.0-27.8 s.) reached lowest values in early 1997, after 
a decreasing trend established in early 1994 (Figure 6.1.19). A time series of mean SRP in this 
layer shows this trend clearly (Figure 6.1.24). Decreases in phosphate in the deeper waters could 
persist for long periods of time as the oceanic ecosystem associated with Station ALOHA has 
been hypothesized to be phosphorous limited in recent years (Karl, 1995). Oxygen 
concentrations between 27.0-27.8 s. vary during the decrease of phosphate from early 1994 
through 1997 (Figure 6.1.24) without any apparent correlation. 

4.2 Thermosalinograph 
Thermosalinograph measurements of near-surface temperature (NST) and near-surface 
salinity (NSS), as well as navigation for the 2004 HOT and mooring cruises are presented in 
Figures 6.2.1a to l and Figures 6.2.2a to l. Thermosalinograph data recorded while on station can 
be compromised by ship effects such as temperature changes in the water due to the ship's hull 
and engine temperatures. Salinity can also be influenced by the ship when on station as the ship 
provides a potential source of contamination and disturbs the water being sampled. As explained 
earlier (Section 2.2.2.2), the external temperature data from cruise HOT-157 were flagged as 
uncalibrated due to problems with the system. 

In general, cooler near-surface temperatures, and in most cases saltier near-surface 
salinities were observed at Station ALOHA compared to the data recorded near Oahu. Salinities 
at station ALOHA were higher than 35.2 during the first and third cruise of the year, and they 
were generally below this value for the rest of the cruises. During HOT-159 the salinity 
decreased from 34.8 early in the cruise to nearly 34.4 by the end of the cruise, apparently due to 
rainfall, as indicated by the meteorological observations. 

4.3 Meteorology 
The meteorological data collected at 4-hour intervals by HOT program scientists include 
atmospheric pressure, sea-surface temperature and wet and dry bulb air temperature. These data 
are presented in Figures 6.3.1 to 6.3.3. As described by Winn et al. (1991), parameters show 
evidence of annual cycles, although the daily and weekly ranges are nearly as high as the annual 
range for some variables. Wind speed and direction are also collected on HOT cruises. These 
data are presented in Figures 6.3.4a to l. 

One National Data Buoy Center (NDBC) meteorological buoy (#51001) is located 400 
km west of ALOHA at 23.4N, 162.3W (Figure 1.1). This buoy collects hourly observations of 
air temperature, sea surface temperature, atmospheric pressure, wind speed and direction and 
significant wave height. The coherence of the data from Buoy #51001 with the data collected on 
HOT cruises was examined and reported in Tupas et al. (1993). We concluded from these 

71



analyses, that the data from this buoy can be used to get useful estimates of air temperature, sea 
surface temperature and atmospheric pressure at Station ALOHA when the station is not 
occupied. These data are also plotted in Figures 6.3.1 through 6.3.3. 

The thermosalinograph temperatures obtained at Station ALOHA during cruises are also 
plotted together with the sea-surface meteorological observations in Figure 6.3.1 (lower panel) 
and show good agreement with these measurements. 

The wind vectors from buoy #51001 are plotted together with the ship wind observations 
in Figures 6.3.4a to l. As mentioned earlier, the buoy was not in operation during part of May 
2004. 

4.4 ADCP Measurements 
An overview of the shipboard ADCP data is given by the plots of velocity as a function 
of time and depth while on station (Figures 6.4.1a to k) and velocity as a function of latitude and 
depth during transit to and from Station ALOHA and Station 6, combined (Figures 6.4.2a to k). 
As explained earlier (Section 2.4), gaps in some of the northward transit plots were caused by 
rough weather, and gaps in some of the on-station data are due to excursions to retrieve the 
primary productivity array and floating sediment traps. Cruise HOT-157 did not have ADCP 
data (Section 2.4). As in previous years, currents were highly variable from cruise to cruise and 
within each cruise. 

4.5 Biogeochemistry 
4.5.1 Dissolved Oxygen 
A contour plot of dissolved oxygen concentration in the upper 200 dbar of the water 
column from 1988-2004 based on analyses of water samples collected at discrete depths is 
shown in Figure 6.5.1. Dissolved oxygen shows a seasonal maximum between 60 and 100 m 
depth that develops during the summer-fall. This maximum, presumably of biological origin, is 
typically eroded during the winter. 

4.5.2 Dissolved Inorganic Carbon and Titration Alkalinity 
Time-series of mixed-layer titration alkalinity and DIC from 1988-2004 are presented in 
Figure 6.5.2. A contour plot of dissolved inorganic carbon is shown in Figure 6.5.3 and a 
contour plot of titration alkalinity is shown in Figure 6.5.4. 

Mixed layer titration alkalinity normalized to 35 ppt salinity averages approximately 
2303 eq kg-1. No obvious seasonal or interannual pattern is evident. This observation is 
consistent with the results of Weiss et al. (1982) who concluded that titration alkalinity 
normalized to salinity remains constant in both the North and South Pacific subtropical gyres. In 
contrast to titration alkalinity, the concentration of DIC varies seasonally and interannually. DIC 

72



in the mixed layer is highest in March and April and lowest in September and October. This 
oscillation results from winter mixing of DIC rich waters from below and biological drawdown 
of CO2 in the shallow summer mixed layers (Ishii, M. et al., 2001). Using this data, Dore et al. 
(2003) found a significant decrease in the strength of the CO2 sink between 1989 and 2001 due 
to changes in regional precipitation and evaporation patterns brought on by climate variability. 

4.5.3 Inorganic Nutrients 
Mixed layer nutrient concentrations at Station ALOHA are at or well below the detection 
limits of the autoanalyzer methods. Alternative high-sensitivity analytical techniques were used 
to measure the nanomolar levels of [nitrate + nitrite] and SRP in the upper water column. 

The chemiluminescent method of Cox (1980) as modified for seawater by Garside (1982) 
was used to determine the [nitrate+nitrite] content of near surface (0-200 m interval) water 
samples. Figure 6.5.5 shows the profiles obtained from our low level [nitrate + nitrite] analyses 
at Station ALOHA during 2004. The upper 100 m is generally depleted in [nitrate + nitrite] with 
values usually not exceeding 5 nmol kg-1. A contour plot of LLN from 0-100 dbar during the 
1989-2004 time period is shown in Figure 6.5.6. 

Dissolved inorganic P (DIP) was analyzed using the MAGnesium Induced Coprecipitation 
(MAGIC) method (Karl and Tien 1992). MAGIC improves both the sensitivity 
(detection limit ~ 1 nmol P l-1) and the precision of the low level P (LLP) determination in 
oligotrophic seawaters. Figure 6.5.7 presents the low-level SRP data from 2004. At depths 
shallower than 100 m, SRP is typically less than 100 nmol kg-1. A contour plot of LLP from 0100 
dbar during the period 1989-2004 is shown in Figure 6.5.8. Several trends are evident, 
including a general reduction in DIP concentrations from >90 nmol kg-1 in 1989-1990 to <30 
nmol kg-1 in 2001. The 0-100 m DIP depth integrated inventory was reduced from a high of >10 
mmol P m-2 to a low of <2.5 mmol P m-2. It has been suggested that this long-term, decadalscale 
reduction in DIP is a result of selection for N2 fixation microorganisms with an attendant 
shift from a N-controlled to a P-controlled ecosystem (Karl et al. 2001). Despite this general 
reduction in DIP concentration, there appear to be aperiodic injections of DIP (for example in 
early 1995 and less dramatic increases in 1998, 2000 and 2001). The mechanism(s) controlling 
these inventory enhancements is not well resolved in the HOT field data. 

4.5.4 Dissolved Organic Matter 
A contour plot of dissolved organic carbon (DOC) from 0 to 1000 dbar over the 19882004 
time period is presented in Figure 6.5.9 and contour plots of dissolved organic nitrogen 
(DON) and phosphorus (DOP) from 0 to 1000 dbar over the 1988-2000 time period are 
presented in Figures 6.5.10-6.5.11. DOC concentrations are typically about 70-110 mol kg-1 at 
the surface and decrease to about 40-50 mol kg-1 at 800 m. DON is typically 5-6 mol kg-1 at 
the surface, decreasing to about 2 mol kg-1 at 800 m. DOP is about 0.2-0.3 mol kg-1 at the 
surface and decreases to <0.05 mol kg-1 at 800 m. All three organic nutrients exhibit 
substantial interannual variability. 

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4.5.5 Particulate Bioelements 
4.5.5.1 Particulate Carbon, Nitrogen and Phosphorus 
Particulate carbon (PC), nitrogen (PN) and phosphorus (PP) concentrations in the surface 
ocean over the 16 years of the program are shown in Figures 6.5.12-6.5.17. PC ranges from 
about 1-3 mol kg-1, PN from 0.1-0.6 mol kg-1 and PP from 10-25 nmol kg-1 in the upper 100 m 
of the water column. An annual cycle is suggested with the greatest particulate bioelement 
concentrations in summer/fall and the lowest in winter. Substantial interannual variability is also 
noted, especially for PP. 

4.5.5.2 Particulate Biogenic Silica 
Particulate biogenic silica (PSi) concentrations in the surface ocean over the last 8 years 
of the program are shown in Figure 6.5.18 and Figure 6.5.19. PSi typically ranges from < 5 to 
about 25 nmol kg-1 in the upper 100 m of the water column. During the summer months in 1998 
and 2000, PSi increased dramatically in the upper 50 m of the water. This feature appears 
associated with a large bloom of diatoms, as evidenced from the sharp increases in fucoxanthin 
(Figure 6.5.22). 

4.5.6 Pigments 
4.5.6.1 Standard Fluorometric Method 
A contour plot of chlorophyll a concentrations measured using standard fluorometric 
techniques from 0 to 200 dbar during 1988-2004 is shown in Figure 6.5.20. A chlorophyll 
maximum with concentrations up to about 0.3 mg m-3 is observed at approximately 110 m depth. 
The magnitude of this feature exhibits significant interannual variability, with a pronounced 
period of low chlorophyll concentration lasting from 1992-1998. Chlorophyll a concentrations 
at depths shallower than 50 m display an annual cycle with winter maxima and summer minima. 

4.5.6.2 High Performance Liquid Chromatography 
Contour plots of HPLC-determined pigment concentrations from 0 to 200 dbar during 
1988-2004 are shown in Figures 6.5.21-6.5.23. The pigments have been segregated into three 
chromophore classes: chlorophylls (chlorophyll a, chlorophyll b, and chlorophyll c; Figure 
6.5.21), photosynthetic carotenoids (19-butanoyloxyfucoxanthin, fucoxanthin, and 19hexanoyloxyfucoxanthin; 
Figure 6.5.22) and photo-protective carotenoids (diadinoxanthin, 
zeaxanthin, and a/-carotene; Figure 6.5.23). 

Chlorophyll a includes contributions by monovinyl and divinyl chlorophyll a and serves 
as a proxy for phytoplankton community biomass. Chlorophyll b includes contributions by 
monovinyl and divinyl chlorophyll b and is primarily derived from Prochlorococcus spp. since 
chlorophyll b-containing eukaryotes (e.g., chlorophytes and prasinophytes) are relatively rare at 

74



Station ALOHA as evidenced by the low and variable concentrations of lutein (chlorophyte 
marker) and prasinoxanthin (prasinoxanthin marker) (data not shown). Chlorophyll c includes 
contributions by chlorophylls c1+c2+c3 and serves as a proxy for chromophyte microalgal 
biomass (e.g., haptophytes, pelagophytes and diatoms). Photosynthetic carotenoids are typically 
useful for distinguishing phytoplankton at the Class level and the dominant species found at 
Station ALOHA include 19-butanoyloxyfucoxanthin (pelagophyte marker), fucoxanthin 
(diatom marker), and 19-hexanoyloxyfucoxanthin (haptophyte marker). The photo-protective 
carotenoids, diadinoxanthin, zeaxanthin, and a/-carotene are respectively associated with 
chromophyte microalgae, cyanobacteria (e.g., Prochlorococcus, Synechococcus and 
Trichodesmium spp.), and all members of the phytoplankton community. 

Pigment distributions display distinct temporal patterns at Station ALOHA, with highest 
pelagophyte abundances during the periods 1989-1991 and 1996-2002. For other key groups, 
such as the haptophytes and cyanobacteria, there appears to be a recent post-1996 enhancement 
in their biomass relative to the previous 7-year period of observation. Diatoms, on the other 
hand, display sharp increases during the summer months of certain years (e.g., 1998 and 2000). 
These interannual variations in phytoplankton populations are likely linked to climate forcing 
(e.g., ENSO and PDO) and are currently under investigation. 

4.5.6.3 Chlorophyll a, b, c 
Contour plots of TD-700 analyzed chlorophylls a, b and c from 0 to 200 meters are 
shown in Figure 6.5.24. For every pigment, a maximum is observed at approximately 120 
meters. Chlorophyll a concentrations by fluorometry show an annual cycle with winter maxima 
and summer minima. During HOT-116 (June 2000), chlorophyll a concentrations increased 
dramatically in the upper 45 m of the water. This feature appears associated with a large bloom 
of diatoms, as evidenced from the sharp increases in chlorophyll c, particulate silica (Figure 
6.5.19) and fucoxanthin (Figure 6.5.22). 

4.5.6.4 Phycoerythrin 
Contour plots of the 0.4m, 5m and 10m fractions of phycoerythrin from 0 to 200 
meters are shown in Figure 6.5.25. While the > 0.4m and > 5m fractions do not appear to 
show any type of seasonality or gradation in the upper ocean, the > 10m fraction appears to 
show a late fall bloom of either Trichodesmium or aggregates containing cyanobacteria. 

4.5.7 Adenosine 5'-triphosphate 
The concentration of particulate ATP resembles those of the particulate bioelements, 
showing maximum concentrations near the surface and a decreasing profile with depth (Figure 
6.5.26). Surface ocean ATP varies between years more than three-fold, with conspicuously high 
levels noted in 1994-1995. 

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4.6 Biogeochemical Rate Measurements 
4.6.1 Primary Production 
The depth-integrated (0-200 m) results of the 14C incubations and pigment determinations 
for samples collected from CTD casts in 2004 are presented in Table 4.1. Also included for each 
cruise is the incubation duration and the total incident irradiance (400-700 nm) measured on the 
deck of the ship during the incubation period. Integrated primary production rates measured 
over all 16 years of the program are shown in Figure 6.6.1. A contour plot is shown in Figure 

6.6.2. Depth-integrated rates of primary production vary seasonally, with summer maxima and 
winter minima. Overall, primary production varies by approximately a factor of five, ranging 
from ~200 to 1000 mg C m-2 d-1. The mean ( sd) depth integrated primary production for the 
entire 16 year data set is 512  149 mg C m-2 d-1. Although this value is higher than historical 
measurements for the oceanic central gyres (Ryther 1969), it is consistent with more recent 
measurements (Martin et al., 1987; Laws et al., 1989; Knauer et al., 1990). 
Table 4.1: Primary production and pigment summary integrated values (0-200 m) 

HOT 
LICOR 
Irradiance 
PRR 
Irradiance 
Pigments 
(mg m-2) 
Incubation 
Duration 
(hrs) 
Light Assimilation 
Rates 
(mg C m-2 d-1)(E m-2 d-1) (E m-2 d-1) Chl a Pheo 
155 10.67 9.18 22.1 31.3 12.25 278 
156 20.70 18.39 17.2 25.7 12.25 324 
157 41.42 38.21 21.8 33.8 13.75 533 
158 54.01 49.01 22.4 31.9 13.00 670 
159 56.81 NA 19.6 34.8 15.00 849 
160 NA NA 19.9 36.7 14.75 651 
162 50.49 50.62 22.8 41.1 14.00 656 
163 42.36 41.51 22.3 36.1 14.00 525 
164 24.85 24.89 25.9 34.3 12.00 570 
165 24.28 24.40 23.1 40.3 11.75 344 
166 17.12 17.09 20.0 34.7 11.25 359 

4.6.2 Particle Flux 
Particulate carbon (PC), nitrogen (PN), phosphorus (PP) and silica (PSi) fluxes at 150 m 
are presented in Table 4.2 and Figure 6.6.3 for the 1988-2004 time period. All four fluxes show 
large month-to-month and interannual variations. The magnitudes of PC and PN fluxes vary by 
about a factor of five, while PP and PSi fluxes varies by about a factor of 20. These particle flux 
measurements are consistent in magnitude with those measured in the central North Pacific 
Ocean during the VERTEX program (Martin et al., 1987; Knauer et al., 1990). However, the 
HOT data set reveals interannual changes not documented by earlier studies. Of particular note 
is the change from a more variable, high-flux time period (1988-1991) to a low-flux low-
variability regime (1992-1996). There is a suggestion in the 1997-2004 data that particle fluxes 
may have increased in magnitude and variability. 

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Table 4.2: Station ALOHA 2004 sediment trap flux data 

PC Flux PN Flux PP Flux PSi Flux 
HOT (mg m-2 d-1) (mg m-2 d-1) (mg m-2 d-1) (mg m-2 d-1) 
Mean SD Mean SD Mean SD Mean SD 
155 17.0 2.4 3.06 0.32 0.108 0.060 2.069 0.588 
156 37.8 4.2 5.21 0.25 0.215 0.041 3.107 0.214 
157 33.0 9.2 4.98 1.17 0.251 0.108 1.814 0.244 
158 33.4 4.3 4.89 0.56 0.201 0.009 3.666 0.623 
159 22.4 3.9 3.27 0.58 0.222 0.033 2.820 0.733 
160 34.1 5.7 5.46 0.99 0.329 0.057 2.463 0.552 
162 23.6 2.9 2.89 0.27 0.118 0.051 7.957 3.064 
163 28.1 3.5 3.93 0.63 0.170 0.041 2.758 0.471 
164 26.1 5.3 4.19 1.00 0.132 0.019 1.575 0.249 
165 22.5 4.5 2.96 0.45 0.137 0.047 2.423 0.195 
166 19.1 2.5 2.70 0.37 0.131 0.040 2.535 1.955 

4.7 Optical Measurements 
4.7.1 Solar Irradiance 
Incident irradiance (400-700 nm wavelength band) measured using a LICOR LI-1000 
during the cruise is shown in Figures 6.7.1a-l (upper panel). Incident irradiance is dependent on 
cloud cover, so it can potentially vary greatly from cruise-to-cruise or even day-to-day. But in 
general, as would be expected, higher values are measured during the summer months (HOT162) 
and lower values in the winter months (HOT-155 & HOT-166). To help interpret the 
results, integrated incident irradiance measured during the Primary Production incubation period 
is included in Table 4.1. 

4.7.2 Downwelling Irradiance and Upwelling Radiance 
Profiles of photosynthetically available radiation (PAR) and PAR attenuation coefficient 
(KPAR) measured using a Biosperical PRR-600 are shown in Figures 6.7.1a-l (lower panels). 
Due to the tendency for the instrument to tilt back-and-forth when brought up through the water 
column, only the downcast profiles are included. Figure 6.7.2 shows time-series of the 1 % light 
level and KPAR during the six years weve been collecting PRR data. Both vary seasonally. The 
average 1 % light-level at Station ALOHA is about 107 m while the average KPAR between 100 
& 150m is 0.0438 m-1. Downwelling irradiance measured during the Primary Production 
incubation period is shown in Table 4.1. The results compare favorably with the integrals 
obtained using the LICOR LI-1000 which also measures PAR. 

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4.7.3 Fast Repetition Rate Fluorometry (FRRF) 
In the North Pacific Subtropical Gyre (NPSG), aperiodic fluctuations in primary 
productivity are difficult to capture using the in situ 14C-primary production measurements. In 
order to determine photosynthetic properties controlling variability in primary production, in 
situ, time-series measurements of Fast Repetition Rate Fluorometry (FRRF) have been 
conducted. Photosynthetic efficiency, as indicated by FV/FM (Figure 6.7.3a-g, left panel), was 
high and constant through the water column (averaging 0.60  0.10), exceeding the theoretical 
maximum (i.e. > 0.65) below the Deep Chlorophyll Maximum Layer (DCML) (0.75  0.10) and 
in some discrete layers between 40 and 70m. Averaged FV/FM through the mixed layer were 
linearly related to mixed layer depth (MLD), suggesting the influence on photosynthetic activity 
by possible nutrient injections. 

The FRRF-derived initial slope of the P vs. E curve (a) (Figure 6.7.3a-g, center panel) 
was approximately six times lower at the surface than at the DCML, highlighting the presence of 
high-and low-light adapted populations. The derived FC (quantum yield of photosynthesis) was 
low (0.0016 mol C mol quanta-1) throughout the year, with maxima in the DCML region. FC 
was significantly related to changes in functionally reaction centers (linear) and in a 
(exponential), and to a lesser extent to FV/FM (linear). Significant (. =  100%) daily variations 
in primary productivity (Figure 6.7.3a-g, right panel), driven by changes in a, were also found in 
a couple cruises. 

These results show a high photosynthetic efficiency in this oligotrophic region, 
highlighting that photoautotrophs may have successfully optimized their photosynthetic 
apparatus to the low nutrient environment. The absorption of light (a), and not the efficiency of 
light utilization (FV/FM), appears to be the physiological parameter driving FC variations, daily 
productivity and to some extent the observed aperiodic variation in the NPSG. (Corno et al. 
2006) 

4.8 Microbial Community Structure 
Depth profiles of heterotrophic bacterial (actually non-pigmented picoplankton and 
archaea) and Prochlorococcus abundances for each cruise are presented in Figure 6.8.1. A 
contour plot is shown in Figure 6.8.2. At the surface, heterotrophic bacterial numbers range from 
4 to 8 x 105 cells ml-1. In most cases bacterial numbers decrease with depth although there are 
some profiles where the numbers remain fairly constant with depth throughout the euphotic 
zone. Prochlorococcus cells are found at concentrations ranging from around 0 to 2 x 105 ml-1 at 
the surface and usually decrease with depth but with a subsurface maximum between 75 and 125 

m. 
Depth profiles of Synechococcus and pigmented eukaryotes are presented in Figure 6.8.3. 
A contour plot is shown in Figure 6.8.4. At the surface, Synechococcus numbers range from 1 to 
3 x 103 ml-1, and decrease with depth with a subsurface maxima between 50 and 100 m. The 
abundances of picoeukaryotes typically ranges from 1 to 3 x 103 ml-1, and similar to 
Synechococcus, the eukaryote populations generally decline with depth, occasionally exhibiting 
a subsurface maximum. 

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4.9 Zooplankton Community Structure 
Temporal variation in mesozooplankton biomass during 2004 is presented in Figures 

6.9.1. Both zooplankton dry weight biomass (upper panel) and wet weight biomass (lower 
panel) are plotted. On average, zooplankton dry weight biomass was 12% of zooplankton wet 
weight biomass during the day and 13% during the night. 
Nighttime dry weight zooplankton biomass during 2004 (mean = 1.36 g DW m-2 
(standard deviation, s = 0.327 g DW m-2)) was approximately 1.63 times that of zooplankton 
collected during the day (mean = 0.887 g DW m-2 (s = 0.268 g DW m-2). Wet weight biomass of 
zooplankton differed similarly during the night (mean = 10.4 g WW m-2 (standard deviation, s = 

2.48 g WW m-2)) and day (mean = 7.43 g WW m-2 (standard deviation, s = 2.31 g WW m-2)), and 
night wet weights were 1.51 times day wet weights. The difference in biomass between 
zooplankton collected during the night and zooplankton collected during the day at Station 
ALOHA was significant for both dry and wet weights (Students T-test, n=11, p<0.01), and was 
caused by the upward migration of deep-living zooplankton and micronekton after sunset. 
Mesozooplankton dry weight biomass averages during HOT year 16 are slightly higher 
than averages for all eleven years of the zooplankton program (1994  2004: night mean = 1.10 g 
DW m-2(s = 0.341 g DW m-2); day mean = 0.705 g DW m-2 (s = 0.277 g DW m-2)). Nighttime 
dry weight biomass was significantly greater during year 16 (2004) than during 1994, 1995, 
1996, 1997, 1998 and 1999 (Mann-Whitney U test, n=12, p=0.05). Nighttime biomass during 
2000, 2001, 2002 and 2003 did not differ significantly from year 15 (2003). This pattern was 
similar for daytime zooplankton biomasses. Daytime dry weight biomass was significantly 
greater during year 16 (2004) than during 1994, 1995, 1996, 1997 and 1999 (Mann-Whitney U 
test, n=12, p=0.05), whereas daytime biomass during 1998, 2000, 2001, 2002 and 2003 did not 
differ significantly from year 16 (2004). 

79



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Campbell, L., H. Nolla and D. Vaulot. 1994. The importance of Prochlorococcus to community structure 
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Cox, R.D. 1980. Determination of nitrate at the parts per billion level by chemiluminescence. Analytical 
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DeMaster, D.J. 1981. The supply and accumulation of silica in the marine environment. Geochimica et 
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Dore, J.E., T. Houlihan, D.V. Hebel, G. Tien, L.M. Tupas and D.M. Karl. 1996. Freezing as a method of 
sample preservation for the analysis of dissolved inorganic nutrients in seawater. Marine Chemistry, 
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Dore, J.E., R. Lukas, D.W. Sadler and D. M. Karl. 2003. Climate-driven changes to the atmospheric 
CO2 sink in the subtropical North Pacific Ocean. Nature 424, 754-757. 

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Garside, C. 1982. A chemiluminescent technique for the determination of nanomolar concentrations of 
nitrate and nitrite in seawater. Marine Chemistry, 11, 159-167. 

Ishii, M. et al. 2001. Seasonal variation in total inorganic carbon and its controlling processes in surface 
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Seasonal and interannual variability in primary production and particle flux at Station ALOHA. 
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phosphorus and total mass analyses used in the US-JGOFS Hawaii Ocean Time-series program, p. 
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Geophysical Monograph 63, American Geophysical Union. 

Karl, D.M. and O. Holm-Hansen. 1978. Methodology and measurement of adenylate energy charge ratios 
in environmental samples. Marine Biology, 48, 185-197. 

Karl, D.M., R. Letelier, D. Hebel, L. Tupas, J. Dore, J. Christian and C. Winn. 1995 Ecosystem changes 
in the North Pacific subtropical gyre attributed to the 1991-92 El Nio. Nature, 373, 230-234. 

Karl, D.M. and R. Lukas. 1996. The Hawaii Ocean Time-series (HOT) program: Background, rationale 
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Karl, D.M. and G. Tien. 1992. MAGIC: A sensitive and precise method for measuring dissolved 
phosphorus in aquatic environments. Limnology and Oceanography, 37, 105-116. 

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Ocean Time-series Program Data Report 7, 1995. School of Ocean and Earth Science and 
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Karl, D.M. and C.D. Winn, 1991. A sea of change: Monitoring the oceans carbon cycle. Environmental 
Science and Technology, 25, 1967-1981. 

Kennan, S.C. and R. Lukas. 1995. Saline intrusions in the intermediate waters north of Oahu, Hawaii. 
Deep-Sea Research, 43, 215-241. 

Knauer, G.A., J.H. Martin and K.W. Bruland. 1979. Fluxes of particulate carbon, nitrogen and 
phosphorus in the upper water column of the northeast Pacific. Deep-Sea Research, 26, 97-108. 

Knauer, G.A., D.G. Redalje, W.G. Harrison and D.M. Karl. 1990. New production at the VERTEX time-
series site. Deep-Sea Research, 37, 1121-1134. 

Landry, M.R., H. Al-Mutairi, K.E. Selph, S. Christensen and S, Nunnery. 2001. Seasonal patterns of 
mesozooplankton abundance and biomass at Station ALOHA. Deep-Sea Research II, 48, 2037-2062. 

Laws, E.A., G.R. DiTullio, P.R. Betzer, D.M. Karl and K.L. Carder. 1989. Autotrophic production and 
elemental fluxes at 26 N, 155 W in the North Pacific subtropical gyre. Deep-Sea Research, 36, 103


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Lukas, R. and S. Chiswell. 1991. Submesoscale water mass variations in the salinity minimum of the 
north Pacific near Hawaii. WOCE Notes, 3(1), 6-8. 
Lukas, R., F. Santiago-Mandujano, F. Bingham and A. Mantyla. 2001. Cold bottom water events 
observed in the Hawaii Ocean Time-series: implications for vertical mixing. Deep-Sea Res. I, 48: 
995-1021. 

Lukas, R. 2001. Freshening of the upper thermocline in the North Pacific subtropical gyre associated with 
decadal changes of rainfall. Geophys. Res. Lett., 28, 3485-3488. 

Lukas R. and F. Santiago-Mandujano. 2001. Extreme water mass anomaly observed in the Hawaii Ocean 
Time-series. Geophys. Res. Lett., 28, 2931-2934. 

Martin, J.H., G.A. Knauer, D.M. Karl and W.W. Broenkow. 1987. VERTEX: Carbon cycling in the 
northeast Pacific. Deep-Sea Research, 34, 267-285. 

Michaels, A. and A. Knap. 1996. Overview of the U.S.-JGOFS Bermuda Atlantic Time-series Study and 
Hydrostation S program. Deep-Sea Research, 43, 157-198. 

Monger, B,C, and M.R. Landry. 1993. Flow cytometry analysis of marine bacteria with Hoechst 3342. 
Applied and Environmental Microbiology, 59, 905-911. 

National Research Council. 1984a. Global Observations and Understanding of the General Circulation of 
the Oceans: Proceedings of a Workshop, National Academy Press, Washington, DC, 418 pp. 

National Research Council. 1984b. Global Ocean Flux Study: Proceedings of a Workshop, National 
Academy Press, Washington, DC, 360 pp. 

Ortner, P.B. E.M. Hulbert and P.H. Wiebe. 1979. Gulf Stream rings, phytohydrography and herbivore 
habitat contrasts. Journal of Experimental Marine Biology and Ecology, 39, 101-124. 

Owens, W.B. and R.C. Millard. 1985. A new algorithm for CTD oxygen calibration. Journal of Physical 
Oceanography, 15, 621-631. 

Plueddemann, A. J., R. A. Weller, R. Lukas, J. Lord, P. R. Bouchard, and M. A. Walsh, 2006. WHOI 
Hawaii Ocean Timeseries Station (WHOTS): WHOTS-2 Mooring Turnaround Cruise Report. Woods 
Hole Oceanographic Institution Technical Report, WHOI-2006-XX, UOP Technical Report 06-XX, 
72 pp. 

Qian, J. and K. Mopper. 1996. Automated high-performance, high-temperature combustion total organic 
carbon analyzer. Analytical Chemistry, 68, 3090-3097. 

Ryther, J.H. 1969. Photosynthesis and fish production in the sea. The production of organic matter and its 
conversion to higher forms of life vary throughout the world ocean. Science, 166, 72-76. 

Santiago-Mandujano, F., L. Tupas, C. Nosse, D. Hebel, L. Fujieki, R. Lukas, D. Karl, 1999. Hawaii 
Ocean Time-series Data Report 10, 1998, School of Ocean and Earth Science and Technology, 
University of Hawaii, 246 pp. In: R. Lukas and D. Karl, 1999. Hawaii Ocean Time-series. A Decade 
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Time-series Data Report 11, 1999, School of Ocean and Earth Science and Technology, University of 
Hawaii, 191 pp.. 

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Plan. JGOFS Report No. 5. International Council of Scientific Unions, 61 pp. 

Strickland, J.D.H. and T.R. Parsons. 1972. A Practical Handbook of Seawater Analysis. Fisheries 
Research Board of Canada, 167 pp. 

Tsuchiya, M. 1968. Upper Waters of the Intertropical Pacific Ocean. Johns Hopkins Oceanographic 
Studies, 4, 49 pp. 

Tupas, L., F. Santiago-Mandujano, D. Hebel, E. Firing, F. Bingham, R. Lukas and D. Karl. 1994. Hawaii 
Ocean Time-series Program Data Report 5, 1993. School of Ocean and Earth Science and 
Technology, University of Hawaii, 156 pp. 

Tupas, L., F. Santiago-Mandujano, D. Hebel, E. Firing, R. Lukas and D. Karl. 1995. Hawaii Ocean Time-
series Data Report 6: 1994. School of Ocean and Earth Science and Technology, University of 
Hawaii, 199 pp. 

Tupas, L., F. Santiago-Mandujano, D. Hebel, R. Lukas, D. Karl and E. Firing. 1993. Hawaii Ocean Time-
series Program Data Report 4, 1992. School of Ocean and Earth Science and Technology, 
University of Hawaii, 248 pp. 

Tupas, L., F. Santiago-Mandujano, D. Hebel, C. Nosse, L. Fujieki, E. Firing, R. Lukas and D. Karl. 1997. 
Hawaii Ocean Time-series Program Data Report 8, 1996. School of Ocean and Earth Science and 
Technology, University of Hawaii, SOEST 96-4, 296 pp. 

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Technical Papers in Marine Science, No. 36., UNESCO, Paris. 

Weiss, R.F., R.A. Jahnke and C.D. Keeling. 1982. Seasonal effects of temperature and salinity on the 
partial pressure of CO2 in seawater. Nature, 300, 511-513. 

Winn, C., S.M. Chiswell, E. Firing, D. Karl, R. Lukas. 1991. Hawaii Ocean Time-series Program Data 
Report 2, 1990. School of Ocean and Earth Science and Technology, University of Hawaii, SOEST 
92-01, 175 pp. 

Winn, C., R. Lukas, D. Karl, E. Firing. 1993. Hawaii Ocean Time-series Program Data Report 3, 1991. 
School of Ocean and Earth Science and Technology, University of Hawaii, SOEST 93-3, 228 pp. 

Wright, S.W., S.W. Jeffrey, R.F.C. Mantoura, C.A. Llewellyn, T. Bjornland, D. Repeta and N. 
Welschmeyer. 1991. Improved HPLC method for the analysis of chlorophylls and carotenoids from 
marine phytoplankton. Marine Ecology Progress Series, 77, 183-196. 

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6.0 FIGURES 
6.1 Hydrography 
Figure 6.1.1a-l: [Upper left panel] Temperature, salinity, oxygen and potential density (s.) as a 
function of pressure for the PO deep cast at Station ALOHA for each HOT cruise. [Upper 
right panel] Plot of bottle dissolved oxygen as a function of potential temperature for all 
water samples. [Lower left panel] CTD temperature and salinity plotted as a function of 
pressure to 1000 dbar for all casts at ALOHA. [Lower right panel] Salinity and oxygen from 
CTD and water samples plotted as a function of potential temperature. Only the CTD oxygen 
traces in which bottle oxygen samples were taken are included. 

Figure 6.1.2a-l: [1st panel] Stack plots of temperature versus pressure to 1000 dbar at Station 
ALOHA. Temperatures have been offset by 2 C for clarity. [2nd panel] Stack plots of 
salinity versus pressure to 1000 dbar at Station ALOHA. Salinities have been offset by 0.1 
for clarity. 

Figure 6.1.3a-l: Stack plots of CTD chloropigment (fluorescence) and bottle fluorometric 
chlorophylls+pheopigments versus pressure to 200 dbar [1st panel] and versus s. to 25.5 
kg/m3 [2nd panel] at Station ALOHA. Chloropigment values have been offset by 0.2 g/l for 
both plots. 

Figure 6.1.4a-l: [Upper left panel] Temperature, salinity, oxygen and potential density (s.) as a 
function of pressure for the cast at Station Kahe for each HOT cruise (except for l). [Upper 
right panel] Plot of CTD and bottle dissolved oxygen and salinity as a function of potential 
temperature for water samples at Station Kahe. [Lower left panel] Plot of temperature, 
salinity, oxygen, and s. as a function of pressure at Station Kaena (except for c, g, and h). 
[Lower right panel] Plot of CTD and bottle salinity and oxygen as a function of potential 
temperature at Station Kaena (except for c, g, and h). 

Figure 6.1.5: [Upper panel] Potential temperature versus pressure for all deep casts in 2004. 
[Lower panel]: Potential temperature versus pressure deeper than 2500 dbar for all deep casts 
in 2004. 

Figure 6.1.6: [Upper panel] Salinity versus potential temperature for all deep casts in 2004. 
[Lower panel]: Salinity versus potential temperature for all deep casts in 2004 in the 1-5 C 
range. 

Figure 6.1.7: [Upper panel] Oxygen concentrations from calibrated oxygen sensor data versus 
potential temperature for all deep casts in 2004. [Lower panel] Oxygen versus potential 
temperature for all deep casts in 2004 in the 1-5 C range. 

Figure 6.1.8: Contour plot of CTD potential temperature versus pressure for HOT cruises 1-166. 

Figure 6.1.9: Contour plot of s., calculated from CTD pressure, temperature and salinity, versus 
pressure for HOT cruises 1-166. 

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Figure 6.1.10: Contour plot of CTD salinity versus pressure for HOT cruises 1-166. 

Figure 6.1.11: Contour plot of CTD salinity versus s. to 27.5 s. for HOT cruises 1-166. A heavy 
line connects the average s. at the sea surface. 

Figure 6.1.12: Contour plot of bottle salinity versus pressure for HOT cruises 1-166. The solid 
circles indicate location of samples in the water column. 

Figure 6.1.13: Contour plot of bottle salinity versus s. to 27.5 s. for HOT cruises 1-166. A 
heavy line connects the average s. at the sea surface. 

Figure 6.1.14: Contour plot of bottle oxygen versus pressure for HOT cruises 1-166. The solid 
circles indicate location of samples in the water column. 

Figure 6.1.15: Contour plot of bottle oxygen versus s. to 27.5 s. for HOT cruises 1-166. A 
heavy line connects the average s. at the sea surface. 

Figure 6.1.16: Contour plot of [nitrate + nitrite] versus pressure for HOT cruises 1-123. The solid 
circles indicate location of samples in the water column. 

Figure 6.1.17: Contour plot of [nitrate + nitrite] versus s. to 27.5 s. for HOT cruises 1-123. A 
heavy line connects the average s. at the sea surface. 

Figure 6.1.18: Contour plot of [nitrate + nitrite] versus s. from 27.0 to 27.8 s. for HOT cruises 
1-123. 

Figure 6.1.19: Contour plot of soluble reactive phosphorus versus s. from 27.0 to 27.8 s. for 
HOT cruises 1-123. 

Figure 6.1.20: Contour plot of soluble reactive phosphorus versus pressure for HOT cruises 1


123. The solid circles indicate location of samples in the water column. 
Figure 6.1.21: Contour plot of soluble reactive phosphorus versus s. to 27.5 s. for HOT cruises 
1-123. A heavy line connects the average s. at the sea surface 

Figure 6.1.22: Contour plot of silicate versus pressure for HOT cruises 1-123. The solid circles 
indicate location of samples in the water column. 

Figure 6.1.23: Contour plot of silicate versus s. to 27.5 s. for HOT cruises 1-123. A heavy line 
connects the average s. at the sea surface. 

Figure 6.1.24: Time series of mean bottle dissolved oxygen for HOT cruises 1-166 (upper panel), 
and [nitrate + nitrite] (middle panel) and soluble reactive phosphorus (lower panel) for HOT 
cruises 1-123 between 27.0 and 27.8 s. isopycnals. The smooth line is the spline fit to the 
data. The asterisks indicate the annual mean. 

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6.2 Thermosalinograph 
Figure 6.2.1a-l: Thermosalinograph data for each HOT cruise in 2004. Continuous near-surface 
temperature, salinity and s. (continuous lines), CTD data at the depth of the 
thermosalinograph water intake (circles), and salinity bottle data (crosses). The section 
between the vertical dashed lines indicates the period when Station ALOHA was occupied. 

Figure 6.2.2a-l: Navigation data during each HOT cruise in 2004: latitude, longitude and ship 
speed. The section between the vertical dashed lines indicates the period when Station 
ALOHA was occupied. 

6.3 Meteorology 
Figure 6.3.1: [Upper panel] Atmospheric pressure while at Station ALOHA for 2004 HOT 
cruises (open circles), and NDBC buoy #51001 hourly measurements throughout the year 
(continuous line). [Lower panel] Sea surface temperature measured from a bucket sample 
while at Station ALOHA for 2004 HOT cruises (open circles), NDBC buoy #51001 hourly 
measurements throughout the year (continuous thin line), and near-surface temperatures from 
the thermosalinograph while at Station ALOHA during HOT cruises (thick line). 

Figure 6.3.2: [Upper panel] Dry bulb air temperature while at Station ALOHA for 2004 HOT 
cruises (open circles), and NDBC buoy #51001 hourly measurements throughout the year 
(continuous line). [Lower panel] Wet bulb air temperature while at Station ALOHA for 2004 
HOT cruises. 

Figure 6.3.3: [Upper panel] Sea surface temperature minus dry air temperature while at Station 
ALOHA for 2004 HOT cruises (open circles), and NDBC buoy #51001 hourly 
measurements throughout the year (continuous line) . [Lower panel] Relative humidity at 
Station ALOHA for 2004 HOT cruises. 

Figures 6.3.4a to l: [Upper panel] True winds measured at Station ALOHA for 2004 HOT 
cruises. [Middle panel] Continuous true wind record from the ships anemometer during 
HOT cruises. [Lower panel] True winds measured by NDBC buoy #51001. The orientation 
of the arrows indicates the wind direction; up is northward, right is eastward. 

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6.4 ADCP Measurements 
Figure 6.4.1a to k: Velocity fields at Station ALOHA. [Upper panel] Hourly averages at 20-m 
depth intervals while the ship was on station. the orientation of each stick gives the direction 
of the current: up is northward and to the right is eastward. [Lower panel] Results of a least-
squares fit of hourly averages to a mean, trend, semi-diurnal and diurnal tides; the on-station 
time-series were not long enough to fit an inertial cycle. In the first column the arrow show 
the mean current and the headless stick shows the sum of the mean plus the trend at the end 
of the station. For each harmonic the current ellipse is shown in the first column. The 
orientation of the stick in the second column shows the direction of the harmonic component 
of the current at the beginning of the station and the arrowhead at the end of the stick shows 
the direction of rotation of the current vector around the ellipse. The gaps in some of the 
station data are due to excursions to retrieve the primary productivity array and floating 
sediment traps. 

Figure 6.4.2a to k: Velocity fields on the transits to and from Station ALOHA and Station 
KAENA. The orientation of each stick gives the direction of the current: up is northward and 
to the right is eastward. Velocity is shown as a function of latitude averaged in 10-minute 
intervals. HOT-157 was conducted on the R/V Kilo Moana, which did not have an ADCP 
system during the cruise. 

6.5 Biogeochemistry 
Figure 6.5.1: Contour plot of bottle dissolved oxygen versus pressure for HOT cruises 1-166 
from 0-200 dbar. Solid dots indicate water column sample locations. 

Figure 6.5.2: [Upper panel] Time series of mean mixed layer titration alkalinity (normalized to 
35 ppt salinity) for HOT cruises 1-166. [Lower panel] Mixed layer dissolved inorganic 
carbon (normalized to 35 ppt salinity) for HOT cruises 1-166. Error bars represent standard 
deviation of pooled samples collected between 0 and 45 dbar. 

Figure 6.5.3: [Upper panel] Contour plot of dissolved inorganic carbon versus pressure for HOT 
cruises 1-166 from 0-200 dbar. Solid dots indicate water column sample locations. [Lower 
panel] Contour plot of dissolved inorganic carbon normalized to 35 ppt salinity. 

Figure 6.5.4: [Upper panel] Contour plot of titration alkalinity versus pressure for HOT cruises 
1-166 from 0-200 dbar. Solid dots indicate water column sample locations. [Lower panel] 
Contour plot of titration alkalinity normalized to 35 ppt salinity. 

Figure 6.5.5: Depth profiles from 0-150 dbar of low-level [nitrate + nitrite] at Station ALOHA 
for 2004 HOT cruises by the high-sensitivity chemiluminescence method. 

Figure 6.5.6: [Upper panel] Contour plot from 0-100 dbar of low-level [nitrate + nitrite] at 
Station ALOHA for HOT cruises 1-166. [Lower panel] 0-100 dbar integral of LLN at Station 
ALOHA for HOT cruises 1-166. 

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Figure 6.5.7: Depth profile from 0-250 dbar of low-level soluble reactive phosphorus at Station 
ALOHA for 2004 HOT cruises by the high-sensitivity magnesium induced coprecipitation 
(MAGIC) method. 

Figure 6.5.8: [Upper panel] Contour plot from 0-100 dbar of low-level soluable reactive 
phosphorus at Station ALOHA for HOT cruises 1-166. [Lower panel] 0-100 dbar integral of 
LLP at Station ALOHA for HOT cruises 1-166. 

Figure 6.5.9: Contour plot from 0-1000 dbar of dissolved organic carbon at Station ALOHA for 
HOT cruises 1-166. Solid dots indicate water column sample locations. 

Figure 6.5.10: Contour plot from 0-1000 dbar of dissolved organic nitrogen at Station ALOHA 
for HOT cruises 1-121. Solid dots indicate water column sample locations. 

Figure 6.5.11: Contour plot from 0-1000 dbar of dissolved organic phosphorus at Station 
ALOHA for HOT cruises 1-121. Solid dots indicate water column sample locations. 

Figure 6.5.12: [Upper panel] Mean concentrations of particulate carbon at Station ALOHA for 
HOT cruises 1-166 from 0-50 dbar. [Lower panel] Mean concentrations of particulate 
carbon at Station ALOHA for HOT cruises 1-166 from 50-100 dbar. Error bars represent 
standard deviation of pooled samples within specified depth ranges. 

Figure 6.5.13: Contour plot from 0-350 dbar of particulate carbon at Station ALOHA for HOT 
cruises 1-166. Solid dots indicate water column sample locations. 

Figure 6.5.14: [Upper panel] Mean concentrations of particulate nitrogen at Station ALOHA for 
HOT cruises 1-166 from 0-50 dbar. [Lower panel] Mean concentrations of particulate 
nitrogen at Station ALOHA for HOT cruises 1-166 from 50-100 dbar. Error bars represent 
standard deviation of pooled samples within specified depth ranges. 

Figure 6.5.15: Contour plot from 0-350 dbar of particulate nitrogen at Station ALOHA for HOT 
cruises 1-166. Solid dots indicate water column sample locations. 

Figure 6.5.16: [Upper panel] Mean concentrations of particulate phosphorus at Station ALOHA 
for HOT cruises 1-166 from 0-50 dbar. [Lower panel] Mean concentrations of particulate 
phosphorus at Station ALOHA for HOT cruises 1-166 from 50-100 dbar. Error bars 
represent standard deviation of pooled samples within specified depth ranges. 

Figure 6.5.17: Contour plot from 0-350 dbar of particulate phosphorus at Station ALOHA for 
HOT cruises 1-166. Solid dots indicate water column sample locations. 

Figure 6.5.18: [Upper panel] Mean concentrations of particulate silica at Station ALOHA for 
HOT cruises 79-166 from 0-50 dbar. [Lower panel] Mean concentrations of particulate silica 
at Station ALOHA for HOT cruises 79-166 from 50-100 dbar. Error bars represent standard 
deviation of pooled samples within specified depth ranges. 

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Figure 6.5.19: Contour plot from 0-200 dbar of particulate biogenic silica at Station ALOHA for 
HOT cruises 79-166. Solid dots indicate water column sample locations. 

Figure 6.5.20: Contour plot from 0-200 dbar of fluorometric chlorophyll a concentrations at 
Station ALOHA for HOT cruises 1-166. Solid dots indicate water column sample locations. 

Figure 6.5.21: Contour plots from 0-200 dbar of HPLC chlorophyll (chlorophyll a, chlorophyll 
b & chlorophyll c) concentrations at Station ALOHA for HOT cruises 1-166. 

Figure 6.5.22: Contour plots from 0-200 dbar of HPLC photosynthetic carotenoid (19'butanoyloxyfucoxanthin, 
fucoxanthin & 19'- hexanoyloxyfucoxanthin) concentrations at 
Station ALOHA for HOT cruises 1-166. 

Figure 6.5.23: Contour plots from 0-200 dbar of HPLC photo-protective carotenoid 
(diadinoxanthin, zeaxanthin & a- plus -carotene) concentrations at Station ALOHA for 
HOT cruises 1-166. 

Figure 6.5.24: Contour plots from 0-200 dbar of TD-700 analyzed chlorophyll a, b & c 
concentrations at Station ALOHA for HOT cruises 111-166. Solid dots indicate water 
column sample locations. 

Figure 6.5.25: Contour plots from 0-200 dbar of TD-700 analyzed phycoerythrin concentrations 
(0.4m, 5m & 10m fractions) at Station ALOHA for HOT cruises 111-166. Solid dots 
indicate water column sample locations. 

Figure 6.5.26: Contour plot from 0-350 dbar of particulate adenosine 5'-triphosphate 
concentrations at Station ALOHA for HOT cruises 1-166. Solid dots indicate water column 
sample locations. 

6.6 Biogeochemical Rate Measurements 
Figure 6.6.1: [Upper panel] Integrated (0-200 m) primary production rates from 1988-2004. 
Filled circles and crosses indicate in situ and on deck incubations, respectively. Solid line 
represents the average production (512 mg C m-2 d-1), dashed lines are  one standard 
deviation (149 mg C m-2 d-1). [Lower panel] 3-point running mean of integrated primary 
production rates. Symbols same as in upper panel. 

Figure 6.6.2: Contour plot from 0-100 m of primary production rates at Station ALOHA for 
HOT cruises 1-166. Solid dots indicate water column sample locations. 

Figure 6.6.3: Particulate carbon flux [Top panel] , Particulate nitrogen flux [2nd panel], 
Particulate phosphorus flux [3rd panel] and Particulate silica flux [Bottom panel] at 150 m 
measured on all HOT cruises from 1988-2004. Error bars represent the standard deviation of 
determinations from triplicate particle interceptor traps. 

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6.7 Optical Measurements 
Figure 6.7.1al: [Upper panel] Incident irradiance (400-700 nm wavelength band) measured 
using a Li-COR LI-1000 data logger during each cruise. The red, blue & green lines 
represent the minimum, average & maximum light value respectively of 10-minute intervals. 
The total incident irradiance measured when the primary production array was out 
(represented by the light-blue shaded area) is also calculated and included at the top of each 
figure. [Lower left panel] Photosynthetically available radiation (PARa : derived from KPAR 
using the average downcast surface light) versus depth for every profile at Station ALOHA. 
[Lower right panel] PAR attenuation coefficient (KPAR) versus depth for every profile at 
Station ALOHA. 

Figure 6.7.2: [Upper panel] Depth of the 1% surface PAR light level for HOT cruises 90-166. 
The solid red light represents the average 1% surface PAR light depth (106.5m) at Station 
ALOHA. [Lower panel] Mean PAR attenuation coefficient (KPAR) for HOT cruises 90-166 
from 100-150m. The solid red line represents the average KPAR (.0438 m-1) at Station 
ALOHA. 

Figure 6.7.3a-g: [Left panel] Vertical profile of photosynthetic efficiency from 0-200 m [Center 
panel] Profile of FRRF-derived initial slope of the P vs. E curve [Right panel] Vertical 
profile of in situ primary productivity rates derived by Fast Repitition Rate Fluorometry 
(FRRF) 

6.8 Microbial Community Structure 
Figure 6.8.1: Depth profiles (0-200 m) of Heterotrophic bacteria (blue) and Prochlorococcus 
numbers (red) measured by flow cytometry at Station ALOHA for 2004. 

Figure 6.8.2: Contour plots from 0-200 dbar of Heterotrophic bacteria [Upper panel] and 
Prochlorococcus numbers [Lower panel] at Station ALOHA for HOT cruises 23-166. Solid 
dots indicate water column sample locations. 

Figure 6.8.3: Depth profiles (0-200 m) of Synechococcus (blue) and Eukaryote numbers (red) 
measured by flow cytometry at Station ALOHA for 2004. 

Figure 6.8.4: Contour plots from 0-200 dbar of Synechococcus [Upper panel] and Eukaryote 
numbers [Lower panel] at Station ALOHA for HOT cruises 23-166. Solid dots indicate water 
column sample locations. 

6.9 Zooplankton Community Structure 
Figure 6.9.1: Dry weight biomass [Upper panel] and wet weight biomass [Lower panel] of 
mesozooplankton collected at Station ALOHA during 2004. Nighttime (blue) and daytime 
(red) biomass are plotted. Error bars are the standard deviation for three replicate tows. 

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7.0 HOT PROGRAM PRESENTATIONS AND PUBLICATIONS 
The following is a listing of Presentations & Publications as of September 2006. For an up-todate 
listing please refer to our Web site (hahana.soest.hawaii.edu/hot/hotpub.html). 

7.1 Invited Presentations and Published Abstracts 
1. 1988 Karl, D. NSF-sponsored symposium on Dissertations in Chemical Oceanography, 
"Research opportunities in Hawaiian waters", Honolulu, Hawaii, November 1988. 
2. 1988 Karl, D. NSF/GOFS-sponsored workshop on sediment traps, "Determination of total 
C, N, P flux" and "Screens: A potential solution to the problem of swimmers", Gulf Coast 
Research Laboratory, Mississippi, November 1988. 
3. 1989 Winn, C. D., S. Chiswell, D. M. Karl and R. Lukas. Long time-series research in the 
Central Pacific Ocean. The Oceanography Society 1st Annual Meeting, Monterey, 
California. 
4. 1990 Karl, D., R. Letelier, D. Bird, D. Hebel, C. Sabine and C. Winn. An Oscillatoria 
bloom in the oligotrophic North Pacific Ocean near the GOFS station ALOHA. EOS, 
Transactions of the American Geophysical Union 71, 177-178. 
5. 1990 Winn, C. D., D. Hebel, R. Letelier, D. Bird and D. Karl. Variability in 
biogeochemical fluxes in the oligotrophic central Pacific: Results of the Hawaii Ocean 
Time- Series Program. EOS, Transactions of the American Geophysical Union 71, 190. 
6. 1990 Chiswell, S. M. and R. Lukas. The Hawaii Ocean Time-series (HOT). EOS, 
Transactions of the American Geophysical Union 71, 1397. 
7. 1990 Karl, D. "JGOFS time-series programs," San Francisco, California, December 1990. 
8. 1991 Winn, C., C. Sabine, D. Hebel, F. Mackenzie and D. M. Karl. Inorganic carbon 
system dynamics in the central Pacific Ocean: Results of the Hawaii Ocean Time-series 
program. EOS, Transactions of the American Geophysical Union 72, 70. 
9. 1991 Lukas, R. Water mass variability observed in the Hawaii Ocean Time Series. EOS, 
Transactions of the American Geophysical Union 72, 70. 
10. 1991 Letelier, R., D. Karl, R. Bidigare, J. Christian, J. Dore, D. Hebel and C. Winn. 
Temporal variability of phytoplankton pigments at the U.S.-JGOFS station ALOHA (22 
45'N, 158 W). EOS, Transactions of the American Geophysical Union 72, 74. 
11. 1991 Karl, D. "The Hawaii Ocean Time-series program: Carbon production and particle 
flux", The Oceanography Society 2nd Annual Meeting, St. Petersburg, Florida, March 
1991. 
12. 1991 Karl, D. NATO symposium on Biology and Ecology of Diazotrophic Marine 
Organisms, "Trichodesmium blooms and new nitrogen in the North Pacific gyre", 
Bamberg, Germany, May 1991. 
13. 1992 Anbar, A. D. Rhenium in seawater: Confirmation of generally conservative behavior. 
EOS, Transactions of the American Geophysical Union 73, 278. 
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14. 1992 Schudlich, R. and S. R. Emerson. Modelling dissolved gases in the subtropical upper 
ocean: JGOFS/WOCE Hawaiian Ocean Time-series. EOS, Transactions of the American 
Geophysical Union 73, 287. 
15. 1992 Tupas, L. M., B. N. Popp and D. M. Karl. Dissolved organic carbon in oligotrophic 
waters: experiments on sample preservation, storage and analysis. EOS, Transactions of the 
American Geophysical Union 73, 287. 
16. 1992 Karl, D., C. Winn, D. Hebel, R. Letelier, J. Dore and J. Christian. The U.S.- JGOFS 
Hawaii Ocean Time-Series (HOT) program. American Society for Limnology and 
Oceanography Aquatic Sciences Meeting, Santa Fe, NM, February 1992. 
17. 1992 Campbell, L., R. R. Bidigare, R. Letelier, M. Ondrusek, S. Hall, B. Tsai and C. Winn. 
Phytoplankton population structure at the Hawaii Ocean Time-series station. American 
Society for Limnology and Oceanography Aquatic Sciences Meeting, Santa Fe, NM, 
February 1992. 
18. 1992 Karl, D. NSF-sponsored GLOBEC scientific steering committee meeting, "Hawaii 
Ocean Time-series (HOT) program: A GLOBEC 'Blue Water' initiative", Honolulu, 
Hawaii, March 1992. 
19. 1992 Karl, D. IGBP International Symposium on Global Change, "Oceanic ecosystem 
variability: Initial results from the JGOFS Hawaii Ocean Time-series (HOT) experiment", 
Tokyo, Japan, March 1992. 
20. 1992 Karl, D. Conoco HOT Topics Seminar Series, "The U.S.-JGOFS Hawaii Ocean 
Time- Series (HOT) Program: Biogeochemical Vignettes from the Oligotrophic North 
Pacific Ocean" and "Temporal Variability in Bioelement Flux at Station ALOHA (22 45'N, 
158 W)", Woods Hole, Massachusetts, May 1992 
21. 1992 Bidigare, R. R., L. Campbell, M. Ondrusek, R. Letelier and D. Vaulot. 
Characterization of picophytoplankton at Station ALOHA (22 45'N, 158 W) using HPLC, 
flow cytometry and immunofluorescence techniques. PACON 1992 Meeting, June 1992. 
22. 1992 Winn, C. D., D. Hebel, R. Letelier, J. Christian, J. Dore, R. Lukas and D. M. Karl. 
Long time-series measurements in the central North Pacific: Results of the Hawaii Ocean 
Time-series program. PACON conference, Kona, Hawaii, June 1992. 
23. 1993 Atkinson, M. J. A potentiometric solid state sensor for oceanic CTDs, Abstract of The 
Oceanography Society Annual Meeting, Seattle, Washington, April 1993. 
24. 1993 Campbell, L., H. A. Nolla and D. Vaulot. Microbial biomass in the subtropical central 
North Pacific Ocean (Station ALOHA): The importance of Prochlorococcus, Abstract of 
The Oceanography Society Annual Meeting, Seattle, Washington, April 1993. 
25. 1993 Emerson, S., P. Quay, C. Stump, D. Wilbur and R. Schudlich. Oxygen cycles and 
productivity in the oligotrophic subtropical Pacific Ocean. Abstract of of the Oceanography 
SocietyAnnual Meeting, Seattle, Washington, April 1993. 
26. 1993 Sharp, J. H., R. Benner, L. Bennett, C. A. Carlson, S. E. Fitzwater, E. T. Peltzer, and 
L. Tupas. Dissolved organic carbon: Intercalibration of analyses with equatorial Pacific 
samples. Abstract of The Oceanography Society Annual Meeting, Seattle, Washington, 
April 1993. 
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27. 1993 Winn, C. D., C. J. Carrillo, F. T. Mackenzie and D. M. Karl. Variability in the 
inorganic carbon system parameters in the North Pacific subtropical gyre. Abstract of The 
Oceanography Society Annual Meeting, Seattle, Washington, April 1993. 
28. 1993 Yanagi, K. and D. M. Karl. Note on the fractional determination of TDP in seawater 
by an UV-irradiation method combined with the MAGIC procedure. Abstract of the 
Oceanography Society of Japan annual meeting, Tokyo, Japan, April 1993. 
29. 1993 Campbell, L., H. Liu, R. R. Bidigare and D. Vaulot. Immunochemical 
characterization of Prochlorococcus. Abstract of the American Society of Limnology and 
Oceanography 1993 Annual Meeting, Edmonton, Alberta, Canada, May 1993. 
30. 1993 Christian, J. R. and D. M. Karl. Bacterial exoenzymes in marine waters: Implications 
for global biogeochemical cycles. Abstract of the American Society of Limnology and 
Oceanography 1993 Annual Meeting, Edmonton, Alberta, Canada, May 1993. 
31. 1993 Moyer, C. L., L. Campbell, D. M. Karl and J. Wilcox. Restriction fragment length 
polymorphism (RFLP) and DNA sequence analysis of PCR-generated clones to assess 
diversity of picoeukaryotic algae in the subtropical central North Pacific Ocean (Station 
ALOHA). Abstract of the American Society of Limnology and Oceanography 1993 Annual 
Meeting, Edmonton, Alberta, Canada, May 1993. 
32. 1993 Sharp, J. H., R. Benner, L. Bennett, C. A. Carlson, S. E. Fitzwater and L. Tupas. The 
equatorial Pacific intercalibration analyses of dissolved organic carbon in seawater. 
Abstract of the American Society of Limnology and Oceanography 1993 Annual Meeting, 
Edmonton, Alberta, Canada, May 1993. 
33. 1994 Yuan, J., C. I. Measures and J. A. Resing. Rapid determination of iron in seawater: 
In-line preconcentration flow injection analysis with spectrophotometric detection. EOS, 
Transactions of the American Geophysical Union 75, 25. 
34. 1994 Smith, C. R., S. Garner, D. Hoover and R. Pope. Macrobenthos, mechanisms of 
bioturbation and carbon flux proxies at the abyssal seafloor along the JGOFS Equatorial 
Pacific Transect. EOS, Transactions of the American Geophysical Union 75, 70. 
35. 1994 Farrenkopf, A. M., G. W. Luther, III and C. H. Van Der Weijden. Vertical 
distribution of dissolved iodine species in the northwest Indian Ocean. EOS, Transactions 
of the American Geophysical Union 75, 78. 
36. 1994 Campbell, L., C. D. Winn, R. Letelier, D. Hebel and D. M. Karl. Temporal variability 
in phytoplankton fluorescence at Station ALOHA. EOS, Transactions of the American 
Geophysical Union 75, 100. 
37. 1994 Winn, C., F. T. Mackenzie, C. Carrillo, T. Westby and D. M. Karl. Air-sea carbon 
dioxide exchange at Station ALOHA. EOS, Transactions of the American Geophysical 
Union 75, 112. 
38. 1994 Lukas, R., F. Bingham and A. Mantyla. An anomalous cold event in the bottom water 
observed north of Oahu. EOS, Transactions of the American Geophysical Union 75, 205. 
39. 1994 Tupas, L. M., B. N. Popp and D. M. Karl. Dissolved organic carbon in oligotrophic 
waters; experiments on sample preservation, storage and analysis. EOS, Transactions of the 
American Geophysical Union 75, 287. 
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40. 1994 Bingham, F.M. Drifter observations of the North Hawaiian Ridge Current. EOS, 
Transactions of the American Geophysical Union 75, 307. 
41. 1994 HOT Program P.I.s, staff and students. The Hawaii Ocean Time-series (HOT) 
program: The first five years, p. 59. Abstract of The Oceanography Society Pacific Basin 
Meeting, Honolulu, Hawaii, July 1994. 
42. 1994 HOT Program P.I.s, staff and students. HOT: a time-series study of carbon cycling in 
the oligotrophic North Pacific, p. 24. Abstract of The Oceanography Society Pacific Basin 
Meeting, Honolulu, Hawaii, July 1994. 
43. 1994 Bidigare, R. R., L. Campbell, M. E. Ondrusek, R. Letelier, D. Vaulot and D. M. Karl. 
Phytoplankton community structure at station ALOHA (22 45'N, 158 W) during fall 1991, 
p. 58. Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, 
July 1994. 
44. 1994 Bingham, F. M. and B. Qiu. Interannual varibility of surface and mixed layer 
properties observed in the Hawaii Ocean Time-series, p. 89. Abstract of The Oceanography 
Society Pacific Basin Meeting, Honolulu, Hawaii, July 1994. 
45. 1994 Bingham, F. M. and R. Lukas. Seasonal cycles of temperature, salinity and dissolved 
oxygen observed in the Hawaii Ocean Time-series, p. 90. Abstract of The Oceanography 
Society Pacific Basin Meeting, Honolulu, Hawaii, July 1994. 
46. 1994 Christian, J. Vertical fluxes of carbon and nitrogen at Station ALOHA, p. 61. 
Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 
1994. 
47. 1994 Dore, J. E. and D. M. Karl. Nitrite distributions and dynamics at Station ALOHA, p. 
60. Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 
1994. 
48. 1994 Firing, E. Currents observed north of Oahu during the first five years of HOT, p. 90. 
Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 
1994. 
49. 1994 Fujieki, L. A., D. V. Hebel, L. M. Tupas and D. M. Karl. Hawaii Ocean Time-series 
Data Organization and Graphical System (HOT-DOGS), p. 61. Abstract of The 
Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 1994. 
50. 1994 Hebel, D. V., F. P. Chavez, K. R. Buck, R. R. Bidigare, D. M. Karl, M. Latasa, M. E. 
Ondrusek, L. Campbell and J. Newton. Do GF/F filters underestimate particulate 
chlorophyll a and primary production in the oligotrophic ocean?, p. 62. Abstract of The 
Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 1994. 
51. 1994 Houlihan, T., J. E. Dore, L. Tupas, D. V. Hebel, G. Tien and D. M. Karl. Freezing as 
a method of preservation for seawater dissolved nutrient and organic carbon samples, p. 62. 
Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 
1994. 
52. 1994 Kennan, S. C. and R. Lukas. Saline intrusions in the intermediate waters north of 
Oahu, p. 91. Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, 
Hawaii, July 1994. 
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53. 1994 Letelier, R. M., J. Dore, C. D. Winn and D. M. Karl. Temporal variations in 
photosynthetic carbon assimilation efficiencies at Station ALOHA (22 45'N; 158 00'W), p. 
60. Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 
1994. 
54. 1994 Liu, H. and L. Campbell. Growth and grazing rates of Prochlorococcus and 
Synechococcus at Station ALOHA measured by the selective inhibitor technique, p. 59. 
Abstract of The Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 
1994. 
55. 1994 Lukas, R. Interannual variability of Pacific deep and bottom waters observed in the 
Hawaii Ocean Time-series, p. 91. Abstract of The Oceanography Society Pacific Basin 
Meeting, Honolulu, Hawaii, July 1994. 
56. 1994 Lukas, R., F. Bingham and E. Firing. Seasonal-to-interannual variability observed in 
the Hawaii Ocean Time-series, p. 28. Abstract of The Oceanography Society Pacific Basin 
Meeting, Honolulu, Hawaii, July 1994. 
57. 1994 Tupas, L. M., B. N. Popp, D. V. Hebel, G. Tien and D. M. Karl. Dissolved organic 
carbon measurements at Station ALOHA measured by high temperature catalytic 
oxidation: Characteristics and variation in the water column, p. 63. Abstract of The 
Oceanography Society Pacific Basin Meeting, Honolulu, Hawaii, July 1994. 
58. 1994 Winn, C. D., F. T. Mackenzie, C. Carrillo and D. M. Karl. Air-sea carbon dioxide 
exchange at Station ALOHA, p. 58. Abstract of The Oceanography Society Pacific Basin 
Meeting, Honolulu, Hawaii, July 1994. 
59. 1994 Liu, H. and L. Campbell. Measurement of growth and mortality rate of Prochloroccus 
and Synechococcus at Station ALOHA using a new selective inhibitor technique. Fifth 
International Phycological Congress, Qingdao, China, July 1994. 
60. 1994 Winn, C., F. T. Mackenzie, C. Carrillo, T. Westby and D. M. Karl. Air-sea carbon 
dioxide exchange at Station ALOHA, p. 112. Abstract of the American Society of 
Limnology and Oceanography 1994 Ocean Sciences Meeting, San Diego, California. 
61. 1994 Measures, C. I., J. Yuan and J. A. Resing. The rapid determination of iron in seawater 
at sub-nanomolar concentrations using in-line preconcentration and spectrophotometric 
detection. Sixth Winter Conference on Flow Injection Analysis, San Diego, CA. 
62. 1994 Measures, C.I., J. Yuan and J. A. Resing. Determination of iron in seawater using in-
line preconcentration and spectrophotometric detection. Workshop on Iron Speciation and 
its Biological Activity, Bermuda Biological Station for Research, Bermuda. 
63. 1995 Corts, M. Y. and H. R. Thierstein. Coccolithophore dynamics during 1994 at the 
JGOFS time series Station ALOHA, Hawaii. 5th International Conference on 
Paleoceanography, Halifax, Canada, Abstract, p. 121. 
64. 1995 Campos, M. L. A. M., T. D. Jickells, A. M. Farrenkopf and G. W. Luther, III. A 
comparison of dissolved iodine cycling at the Bermuda Atlantic Time Series station and 
Hawaii Ocean Time-series station. EOS, Transactions of the American Geophysical Union 
76, S175. 
65. 1995 Yuan, J. Collecting iron samples from well mounted on CTD rosette. EOS, 
Transactions of the American Geophysical Union 76, S175. 
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66. 1995 Michaels, A. F., D. Karl and A. H. Knap. Insights on ocean variability from the 
JGOFS time-series stations. Invited plenary lecture, The Oceanography Society Biennial 
Meeting, April 1995. 
67. 1995 Emerson, S., P. Quay, L. Tupas and D. Karl. Chemical tracers of productivity and 
respiration in the upper ocean at U.S. JGOFS station ALOHA, 10th Anniversary JGOFS 
Science Conference, Villefranche, France, May 1995. 
68. 1995 Michaels, A. F., D. Karl and A. H. Knap. Insights on ocean variability from the 
JGOFS time-series stations. Invited lecture, 10th Anniversary JGOFS Science Conference, 
Villefranche, France, May 1995. 
69. 1995 Karl, D. M. Oceanic carbon cycle and global environmental change: A 
microbiological perspective. Invited plenary talk, 7th International Symposium on 
Microbial Ecology, Santos, Brazil, August 1995. 
70. 1995 Winn, C., D. Sadler and D. M. Karl. Carbon dioxide dynamics at the Hawaii 
JGOFS/WOCE time-series station. International Association for the Physical Sciences of 
the Oceans, Honolulu, Hawaii, August 1995. 
71. 1996 Campbell, L., H. Liu and H. A. Nolla. Picophytoplankton population dynamics at 
Station ALOHA, p. OS65. AGU-ASLO Ocean Sciences Meeting, San Diego, CA, 
February 1996. 
72. 1996 Christian, J. R., J. E. Dore and D. M. Karl. Mixing and nutrient fluxes at the US-
JGOFS Station ALOHA ((22 45'N, 158 00'W), p. OS65. AGU-ASLO Ocean Sciences 
Meeting, San Diego, CA, February 1996. 
73. 1996 Dulaney, T. S. and L. R. Sautter. Sedimentation of planktonic foraminifera: Seasonal 
changes in shell flux north of Oahu, Hawaii, p. OS85. AGU-ASLO Ocean Sciences 
Meeting, San Diego, CA, February 1996. 
74. 1996 Emerson, S. Chemical tracers of biological processes: O2, Ar and N2 mass balance in 
the subtropical Pacific at the HOT station, p. OS85. AGU-ASLO Ocean Sciences Meeting, 
San Diego, CA, February 1996. 
75. 1996 Hebel, D. V., D. M. Karl, J. R. Christian, J. E. Dore, R. M. Letelier, L. M. Tupas and 
C. D. Winn. Seasonal and interannual variability in primary production and particle flux at 
Station ALOHA, p. OS85. AGU-ASLO Ocean Sciences Meeting, San Diego, CA, 
February 1996. 
76. 1996 Karl, D. M.. Alternation of N and P control of new and export production in the 
North Pacific gyre: A hypothesis based on the HOT program data set, p. OS86. AGU- 
ASLO Ocean Sciences Meeting, San Diego, CA, February 1996. 
77. 1996 Lawson, L. M., E. E. Hofmann and Y. H. Spitz. Time series sampling and data 
assimilation in a simple marine ecosystem model, p. OS86. AGU-ASLO Ocean Sciences 
Meeting, San Diego, CA, February 1996. 
78. 1996 Lopez, M. D. G., Y. Zhu and M. E. Huntley. Space-time variability of zooplankton-
sized particle concentrations at the Hawaii Ocean Time-series station (Station ALOHA), p. 
OS85. AGU-ASLO Ocean Sciences Meeting, San Diego, CA, February 1996. 
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79. 1996 Quay, P. D. and H. Anderson. Organic carbon export rates in the subtropical N. 
Pacific, p. OS85. AGU-ASLO Ocean Sciences Meeting, San Diego, CA, February 1996. 
80. 1996 Richman, J. G., R. M. Letelier, M. R. Abbott and D. Pillsbury. Expandable optical 
mooring test at Station ALOHA (22 45'N; 158 00'W), p. OS64. AGU-ASLO Ocean 
Sciences Meeting, San Diego, CA, February 1996. 
81. 1996 Scharek, R., M. Latasa, D. M. Karl and R. R. Bidigare Diatom abundance and vertical 
flux at the US-JGOFS/WOCE Station "ALOHA" in the oligotrophic North Pacific gyre, p. 
OS85. AGU-ASLO Ocean Sciences Meeting, San Diego, CA, February 1996. 
82. 1996 Selph, K. E., M. R. Landry, R. J. Miller and H. A. Al-Mutairi. Temporal variability in 
the mesozooplankton community at ocean Station ALOHA, p. OS85. AGU-ASLO Ocean 
Sciences Meeting, San Diego, CA, February 1996. 
83. 1996 Tersol, V., S. Vink, J. Yuan and C. I. Measures. Variations in iron, aluminium and 
berylium concentrations in surface waters at Station ALOHA, p. OS65. AGU-ASLO Ocean 
Sciences Meeting, San Diego, CA, February 1996. 
84. 1996 Tupas, L. M., M P. Sampson and D. M. Karl. Stable nitrogen isotopic analysis of 
sinking particulate matter at the Hawaii Ocean Time-series site, p. OS86. AGU-ASLO 
Ocean Sciences Meeting, San Diego, CA, February 1996. 
85. 1996 Venrick, E. L.. A comparison between the phytoplankton species from Station 
ALOHA and from the Climax region, p. OS65. AGU-ASLO Ocean Sciences Meeting, San 
Diego, CA, February 1996. 
86. 1996 Winn, C. D. Carbon dioxide dynamics at the Hawaii JGOFS/WOCE time-series 
station: Annual and interannual variability, p. OS64. AGU-ASLO Ocean Sciences 
Meeting, San Diego, CA, February 1996. 
87. 1996 Lukas, R. Low-frequency climate signals emerge in the Hawaii Ocean Time-series. 
WOCE Pacific Workshop. Hyatt Newporter, Newport Beach, CA, 19-23 August 1996. 
88. 1996 Santiago-Mandujano, F. Cold bottom water events observed in the Hawaii Ocean 
Time-series. WOCE Pacific Workshop. Hyatt Newporter, Newport Beach, CA, 19-23 
August 1996. 
89. 1997 Lukas, R. Physical studies at the Hawaii Ocean Time-series (HOT) Station. Ocean 
Climate Time-Series Workshop. Johns Hopkins University, Baltimore, MD, 18-20 March 
1997. 
90. 1997 Bird, D.F., R. Maranger and D.M. Karl. The importance of bacterial consumption by 
algae to marine systems. ASLO-Aquatic Sciences Meeting, Santa Fe, NM, February 1997. 
91. 1997 Karl, D.M., D.V. Hebel and L.M. Tupas. Biogeochemical studies at the Hawaii 
Ocean Time- series (HOT) station ALOHA. Joint GCOS GOOS WCRP Ocean 
Observations Panel for Climate (OOPC), GCOS Report No. 41. 
92. 1998 Letelier, R.M., M.R. Abbott, M.H. Freilich, D.M. Karl, P.J. Flament and R. Lukas. 
Euphotic zone biogeochemical response to a wind-induced upwelling event in the North 
Pacific subtropical gyre. AGU-Ocean Sciences Meeting, San Diego, CA, February 1998. 
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93. 1998 Letelier, R.M. and D.M. Karl. The US-JGOFS Hawaii ocean Time-series (HOT) 
Program; What we have learned over the first decade. AGU-Ocean Sciences Meeting, San 
Diego, CA, February 1998. 
94. 1998 Karl, D. The subtropical North Pacific: New views on an old ocean. Ocean Optics 
XIV Meeting, Kailua-Kona, HI, November 1998. 
95. 1998 Ondrusek, M.E., R.R. Bidigare, D. M. Karl and K. Waters. Predictive models for 
estimating rates of primary production in the subtropical North Pacific Ocean. Ocean 
Optics XIV Meeting, Kailua-Kona, HI, November 1998. 
96. 1999 Karl, D.M., K. Bjorkman, D. Hebel, T. Houlihan and L. Tupas. Seasonal and 
interannual variability in C-N-P stoichiometry of dissolved and particulate matter in the 
subtropical North Pacific Ocean. ASLO Aquatic Sciences meeting, Santa Fe, NM, 
February 1999. 
97. 1999 Karner, M.B., L.T. Taylor, E.F. DeLong and D.M. Karl. Bacterial and archaeal 
distributions at the Hawaii Ocean Time-series Station, ALOHA, in the North Pacific 
Ocean. ASLO Aquatic Sciences meeting, Santa Fe, NM, February 1999. 
98. 1999 Karl, D. M. The subtropical North Pacific: New views on an old ocean. JGOFS North 
Pacific Workshop & SEATS Planning Meeting, Taipei, Taiwan, March 1999. 
99. 2000 Benitez-Nelson, C. R., D. M. Karl and K. O. Buesseler. 234Th derived carbon export 
at Station ALOHA. Ocean Sciences Meeting, San Antonio, TX, January 2000. 
100. 2000 Benitez-Nelson, C. R. and D. M. Karl. Phosphorus cycling in the North Pacific gyre. 
Amirican Geophysical Union Meeting, San Francisco, CA, December 2000. 
101. 2000 Bidigare, R. R., M. E. Ondrusek, M. R. Landry, K. Selph, D. M. Karl and R. Leteleir. 
Seasonal and interannual variations in phytoplankton community structure at Station 
ALOHA. JGOFS Open Sciences Conference on Ocean Biogeochemistry: A New 
Paradigm, Bergen, Norway, April 2000. 
102. 2000 Karl, D. M., D. V. Hebel and L. M. Tupas. Biogeochemical studies at the Hawaii 
Ocean Time-series (HOT) Station ALOHA. International Symposium on Carbon Cycle in 
the North Pacific, Nagoya, Japan, February 2000. 
103. 2000 Karl, D. M., S. Emerson, P. J. Harrison, A. F. Michaels and Y. Nojiri. Temporal 
variability of biogeochemistry. JGOFS Open Science Conference on Ocean 
Biogeochemistry: A New Paradigm, Bergen, Norway, April 2000. 
104. 2000 Letelier, R. M., M. R. Abbott and D. M. Karl. Nutrient supply into the euphotic zone 
as a result of the seasonal solar irradiance cycle: Station ALOHA as a case study. Ocean 
Sciences Meeting, San Antonio TX, January 2000. 
105. 2000 Russ, M. E., N. E. Ostrom, B. Popp, T. M. Rust and D. M. Karl. Mechanisms of N2O 
production in the subtropical North Pacific based on determination of the isotopic 
abundance of N2O and O2. Ocean Sciences Meeting, San Antonio, TX, January 2000. 
106. 2001 Neuer, S., R. Davenport, T. Freudenthal, G. Wefer, O. Llinas, M. J. Rueda, D. K. 
Steinberg, M. H. Conte and D. M. Karl. Differences in Redfield ratios between open ocean 
time series stations and implications for carbon export. ASLO Aquatic Sciences Meeting, 
Albuquerque, NM, February 2001. 
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107. 2001 Smith, JR., K. L., R. J. Baldwin, D. M. Karl and A. Boetius. Benthic community 
responses to seasonal pulses in pelagic food supply: Central North Pacific gyre. ASLO 
Aquatic Sciences Meeting, Albuquerque, NM, February 2001. 
108. 2001 Lukas, R. and F. Santiago-Mandujano. The Source Region for Eddies Influencing the 
Hawaii Ocean Time-series. The Oceanography Society Meeting. Miami Beach, Florida. 
April 2001. 
109. 2001 Lukas, R. Influence of Rainfall on the Subtropical North Pacific Mixed Layer. The 
Oceanography Society Meeting. Miami Beach, Florida. April 2001. 
110. 2002 Karl, D. M., J. E. Dore, T. A. Houlihan, D. V. Hebel and L. A. Fujieki. Seasonal and 
interannual variability in the biological pump at Station ALOHA. AGU Ocean Sciences 
Meeting, Honolulu, HI, February 2002. 
111. 2002 Dore, J. E., L. M. Tupas, J. R. Brum and D. M. Karl. Nitrogen-based and nitrogen 
fixation-based support of export production at Station ALOHA: 1989-2001. AGU Ocean 
Sciences Meeting, Honolulu, HI, February 2002. 
112. 2002 Gasc, A. M. E., P. J. Morris and D. M. Karl. Sources and sinks of hydrogen peroxide 
at Station ALOHA. AGU Ocean Sciences Meeting, Honolulu, HI, February 2002. 
113. 2002 Emerson, S. C. Stump, B. Johnson and D. M. Karl. In situ determination of oxygen 
and nitrogen concentrations in the upper ocean. AGU Ocean Sciences Meeting, Honolulu, 
HI, February 2002. 
114. 2002 Lee, K., D. M. Karl, J.-Z. Zhang and R. Wanninkhof. Global estimates of carbon 
export in the nitrate-depleted tropical and subtropical oceans. AGU Ocean Sciences 
Meeting, Honolulu, HI, February 2002. 
115. 2002 Letelier, R. M., D. M. Karl, M. R. Abbott. R. R. Bidigare and J. S. Nahorniak. 
Temporal variability of light penetration depth at Station ALOHA: Potential effect in 
productivity and phytoplankton community structure in the lower euphotic zone. AGU 
Ocean Sciences Meeting, Honolulu, HI, February 2002. 

116. 2002 Lukas, R., T. Finnigan, D. Luther, M. Merrifield, A.T. Morrison, F. Santiago-
Mandujano , J.M. Toole, S.E. Worrilow. Observations of Internal Tides along the Kaena 
Point Ridge. AGU Ocean Sciences Meeting, Honolulu, HI, February 2002. 
117. 2002 Morris, P. J., P. J. leB. Williams and D. M. Karl, In vitro measurements of net 
community production in the euphotic zone of the subtropical North Pacific. AGU Ocean 
Sciences Meeting, Honolulu, HI, February 2002. 
118. 2002 Santiago-Mandujano F., R. Lukas, S. DeCarlo, and E. Firing. An Internal Tide 
Climatology from the Hawaii Ocean Time-Series. AGU Ocean Sciences Meeting, 
Honolulu, HI, February 2002. 
119. 2002 Lukas, R., and F. Santiago-Mandujano. Temporal Variations of Advection and 
Diffusion Limit Understanding of Biogeochemical Evolution in the North Pacific 
Subtropical Gyre. U.S. JGOFS Ocean Time-series Summit. Vancouver, British Columbia, 
April 2002. 
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120. 2002 Lukas, R., F. Santiago-Mandujano, and L. Zamudio. Water Mass Variability in the 
Hawaii Ocean Time-series. WOCE and Beyond Meeting. San Antonio, Texas. November 
2002. 
121. 2002 Lukas, R., F. Santiago-Mandujano, and E. Firing. Long-Term Hydrographic 
Variations Observed in the Hawaii Ocean Time-series. WOCE and Beyond Meeting. San 
Antonio, Texas. November 2002. 
122. 2002 Stammer, D., S. Park, A. Kohl, R. Lukas, and F. Santiago-Mandujano. ECCO 
Estimates of Large-scale Changes at the Hawaii Ocean Time-series Station. WOCE and 
Beyond Meeting. San Antonio, Texas. November 2002. 
123. 2002 Benitez-Nelson, C. R., T. K. Gregory and D. M. Karl. Upper ocean and mesopelagic 
particulate export at Station ALOHA in the NPSG derived from 234TH. AGU Fall Meeting, 
San Francisco, CA, December 2002. 
124. 2002 Duennebier, F. K., R. Butler, D. M. Karl and R. B. Lukas. New opportunities for 
cabled ocean observatories. AGU Fall Meeting, San Francisco, CA, December 2002. 
125. 2002 Johnson, K. S., V. A. Elrod, S. E. Fitzwater, J. N. Plant, F. P. Chavez, S. J. Tanner, R. 
M. Gordon, D. L. Westphal, K. D. Perry and D. M. Karl. Iron and ecosystem response to 
surface ocean - lower atmosphere interactions in the North Pacific Ocean gyre. AGU Fall 
Meeting, San Francisco, CA, December 2002. 
126. 2002 Juranek, L. W., P. D. Quay and D. M. Karl. Primary productivity rates at Station 
ALOHA determined by 18O labeling and the triple isotope composition of dissolved 
oxygen. AGU Fall Meeting, San Francisco, CA, December 2002. 
127. 2002 Sakamoto, C. M., D. M. Karl, H. W. Jannasch, R. R. Bidigare, R. M. Letelier and K. 
S. Johnson. Nitrate variability measured in situ on the HALE ALOHA open ocean 
mooring: Influence of mesoscale eddy activity on phytoplankton community dynamics. 
AGU Fall Meeting, San Francisco, CA, December 2002. 
128. 2003 Lukas, R. Freshwater Flux Variations and Impacts on the North Pacific Ocean. 
American Geophysical Union Fall Meeting, San Francisco, CA, November 2003. 
129. 2004 Bidigare, R. R., Y. Chao, R. Lukas, R. M. Letelier, S. Christensen and D. M. Karl. 
Temporal variations in phytoplankton community structure and physical forcing at Station 
ALOHA (22.75N, 158W). Abstract of the ASLO/TOS Ocean Research Conference, 
Honolulu, HI, February 2004, p. 16. 

130. 2004 Bjrkman, K. M. and D. M. Karl. Phosphorus uptake kinetics of different natural 
populations of bacterioplankton and eukaryotic phytoplankton in the North Pacific 
Subtropical Gyre. Abstract of the ASLO/TOS Ocean Research Conference, Honolulu, HI, 
February 2004, p. 16. 
131. 2004 Church, M. J., B. D. Jenkins, D. M. Karl, S. M. Short, E. O. Omoregie and J. P. Zehr. 
Diversity and vertical distributions of nitrogen-fixing bacteria in the oligotrophic North 
Pacific Ocean. Abstract of the ASLO/TOS Ocean Research Conference, Honolulu, HI, 
February 2004, p. 28. 

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132. 2004 Clemente, T., K. Bjrkman, E. Dafner, L. Fujieki, N. Jachowski, D. Sadler, G. Corno, 
R. Letelier, M. Church, J. Zehr and D. Karl. Regionalization of the Hawaii Ocean Time-
series (HOT) observations. Abstract of the ASLO/TOS Ocean Research Conference, 
Honolulu, HI, February 2004, p. 29. 
133. 2004 Corno, G., R. M. Letelier, M. R. Abbott and D. M. Karl. Estimation of photosynthetic 
activity, as determined by Fast Repetition Rate Fluorometry (FRRF), in the North Pacific 
Subtropical Gyre (NPSG). Abstract of the ASLO/TOS Ocean Research Conference, 
Honolulu, HI, February 2004, p. 33. 
134. 2004 Fujieki, L. A. and D. M. Karl. HOT-DOGS: A user-friendly interface for access to 
the Hawaii Ocean Time-series data. Abstract of the ASLO/TOS Ocean Research 
Conference, Honolulu, HI, February 2004, p. 53. 
135. 2004 Letelier, R. M., M. R. Abbott, D. M. Karl, J. Nahorniak, R. R. Bidigare and G. Corno. 
Assessing phytoplankton biomass and physiological variability at Station ALOHA (22 
45'N, 158 00'W) using radiance reflectance profiles. Abstract of the ASLO/TOS Ocean 
Research Conference, Honolulu, HI, February 2004, p. 92. 

136. 2006 Bjrkman, K. M. and D. M. Karl. Phosphorus utilization in nutrient enrichment 
experiments: A case for diatoms depleting the surface ocean of phosphorus in the 
oligotrophic North Pacific Subtropical Gyre. ASLO/TOS/AGU Ocean Sciences Meeting, 
Honolulu, HI, February 2006. 
137. 2006 Church, M. J., C. Mahaffey, A. A. Fong, J. P. Zehr, D. M. Karl. Time series 
investigations into the dynamics of nitrogen fixing bacteria and rates of nitrogen fixation 
at Station ALOHA. ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 
2006. 
138. 2006 Clemente, T. M., M. J. Church, D. M. Karl. Spatial and temporal variability in 
plankton size structure along biogeochemical gradients in the Pacific Ocean. 
ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
139. 2006 Colman, A. S., R. E. Blake, Y. Liang, D. M. Karl, K. K. Turekian, M. L. Fogel. 
Phosphate oxygen isotopes and microbial phosphorus cycling in the oceans. 
ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
140. 2006 Dore, J. E., R. Lukas, M. J. Church, D. W. Sadler, R. M. Letelier, D. M. Karl. 
Multiyear decline in surface ocean carbon dioxide at Station ALOHA: Has the efficiency 
of the biological carbon pump increased? ASLO/TOS/AGU Ocean Sciences Meeting, 
Honolulu, HI, February 2006. 

141. 2006 Duennebier, F. K., M. D. Tremblay, D. Harris, J. Jolly, D. Copson, J. Babinec, W 
Doi, R. Lukas, D. M. Karl. The ALOHA cabled observatory. ASLO/TOS/AGU Ocean 
Sciences Meeting, Honolulu, HI, February 2006. 
142. 2006 Fong, A. A., M. J. Church, D. M. Karl, R. Lukas, C. Mahaffey, J. P. Zehr. 
Diazotroph abundance and diversity during a large bloom in the oligotrophic North Pacific 
Gyre. ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 

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143. 2006 Grabowski, E. M., K. M. Bjrkman, M. J. Church, T. M. Clemente, S. E. Curless, L. 
A. Fujieki, T. K. Gregory, A. E. Harlan, C. W. Mahaffey, D. W. Sadler, B. V. W. Watkins, 
D. M. Karl. Meridional variations in dissolved and particulate matter concentrations and 
stoichiometries in the tropical and subtropical Pacific Ocean. ASLO/TOS/AGU Ocean 
Sciences Meeting, Honolulu, HI, February 2006. 
144. 2006 Grabowski, M. W., D. M. Karl, M. J. Church. Iron and phosphorus as controls on 
nitrogen fixation at Station ALOHA. ASLO/TOS/AGU Ocean Sciences Meeting, 
Honolulu, HI, February 2006. 
145. 2006 Hannides, C. C., M. R. Landry. The ALOHA to CLIMAX transect: Understanding 
current vs. historical perspectives of mesozooplankton community structure in the 
Subtropical North Pacific Ocean. ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, 
HI, February 2006. 
146. 2006 Karl, D. M. Biogeochemistry of phosphorus in the North Pacific Subtropical Gyre. 
ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
147. 2006 Letelier, R. M., A. White, D. M. Karl, M. J. Church, J. Christian. Inter-annual to 
decadal variability in soluble reactive phosphorus concentration in the North Pacific 
Subtropical Gyre. ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 
2006. 
148. 2006 Lukas, R., F. Santiago-Mandujano, D. Stammer. Interannual to decadal salinity 
variations observed near Hawaii. ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, 
HI, February 2006. 
149. 2006 Montoya, J. P., A. Hansen, D. M. Karl, J. P. Zehr. Size fractionated rates and 
patterns of nitrogen and carbon fixation in the North Pacific Subtropical Gyre. 
ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
150. 2006 Nahorniak, J., R. M. Letelier, A. Ashe, D. M. Karl, M. J. Church, L. A. Fujieki. In 
situ optical characterization of summer blooms in the North Pacific Subtropical Gyre. 
ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
151. 2006 Sadler, D. W., K. M. Bjrkman, M. J. Church, T. M. Clemente, S. E. Curless, D. G. 
Foley, A. A. Fong, L. A. Fujieki, E. M. Grabowski, T. K. Gregory, D. M. Karl, R. M. 
Letelier, P. J. Lethaby, R. Lukas, C. Mahaffey, S. Maenner, P. M. McAndrew, C. L. 
Sabine, F. Santiago-Mandujano, B. V. W. Watkins. Station ALOHA blooms: 
Biogeochemical characteristics of a large plankton bloom in the oligotrophic North Pacific 
Ocean. ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
152. 2006 Zehr, J. P., J. P. Montoya, C. Short, A. Hansen, B. D. Jenkins, M. J. Church, D. M. 
Karl. Nitrogenase gene expression in the North Pacific Subtropical Gyre. 
ASLO/TOS/AGU Ocean Sciences Meeting, Honolulu, HI, February 2006. 
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7.2 Invited/Contributed Book Chapters and Refereed Publications 
1. 1990 Firing, E. and R. L. Gordon. Deep ocean acoustic Doppler current profiling. In: G. F. 
Appell and T. B. Curtin (eds.), Proceedings of the Fourth IEEE Fourth Working 
Conference on Current Measurement, pp. 192-201. IEEE, New York. 
2. 1990 Giovannoni, S. J., E. F. DeLong, T. M. Schmidt and N. R. Pace. Tangential flow 
filtration and preliminary phylogenetic analysis of marine picoplankton. Applied and 
Environmental Microbiology, 56, 2572-2575. 
3. 1991 Chiswell, S. M. Dynamic response of CTD pressure sensors to temperature. Journal 
of Atmospheric and Oceanic Technology 8, 659-668. 
4. 1991 Karl, D. M., J. E. Dore, D. V. Hebel and C. Winn. Procedures for particulate carbon, 
nitrogen, phosphorus and total mass analyses used in the US-JGOFS Hawaii Ocean Time-
Series Program. In: D.C. Hurd and D. Spencer (eds.), Marine Particles: Analysis and 
Characterization, pp. 71-77. American Geophysical Union, Geophysical Monograph 63. 
5. 1991 Karl, D. M., W. G. Harrison, J. Dore et al. Chapter 3. Major bioelements workshop 
report. In: D. C. Hurd and D. W. Spencer (eds.), Marine Particles: Analysis and 
Characterization, pp. 33-42. American Geophysical Union, Geophysical Monograph 63. 
6. 1991 Karl, D. M. and C. D. Winn. A sea of change: Monitoring the oceans' carbon cycle. 
Environmental Science & Technology 25, 1976-1981. 
7. 1991 Laws, E. A. Photosynthetic quotients, new production and net community production 
in the open ocean. Deep-Sea Research 38, 143-167. 
8. 1991 Sabine, C. L. and F. T. Mackenzie. Oceanic sinks for anthropogenic CO2. 
International Journal of Energy, Environment, Economics 1, 119-127. 
9. 1991 Schmidt, T. M., E. F. DeLong and N. R. Pace. Analysis of a marine picoplankton 
community by 16S rRNA gene cloning and sequencing. Journal of Bacteriology 173, 4371-
4378. 
10. 1992 Anbar, A. D., R. A. Creaser, D. A. Papanastassiou and G. J. Wasserburg. Rhenium in 
seawater: Confirmation of generally conservative behavior. Geochimica et Cosmochimica 
Acta 56, 4099-4103. 
11. 1992 Benner, R., J. D. Pakulski, M. McCarthy, J. I. Hedges and P. G. Hatcher. Bulk 
chemical characteristics of dissolved organic matter in the ocean. Science 255, 1561-1564. 
12. 1992 Chen, R. F. and J. L. Bada. The fluorescence of dissolved organic matter in seawater. 
Marine Chemistry 37, 191-221. 
13. 1992 Karl, D. M. The oceanic carbon cycle: Primary production and carbon flux in the 
oligotrophic North Pacific Ocean. In: Y. Oshima (ed.), Proceedings of the IGBP 
Symposium on Global Change, pp. 203-219. Japan National Committee for the IGBP, 
Waseda University, Tokyo, Japan. 
14. 1992 Karl, D. M., R. Letelier, D. V. Hebel, D. F. Bird and C. D. Winn. Trichodesmium 
blooms and new nitrogen in the North Pacific gyre. In: E. J. Carpenter et al. (eds.), Marine 
Pelagic Cyanobacteria: Trichodesmium and Other Diazotrophs, pp. 219-237. Kluwer 
Academic Publishers, Netherlands. 
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15. 1992 Karl, D. M. and G. Tien. MAGIC: A sensitive and precise method for measuring 
dissolved phosphorus in aquatic environments. Limnology and Oceanography 37, 105-116. 
16. 1992 Quay, P. D., B. Tilbrook and C. S. Wong. Oceanic uptake of fossil fuel CO2: Carbon13 
evidence. Science 256, 74-79. 
17. 1993 Campbell, L. and D. Vaulot. Photosynthetic picoplankton community structure in the 
subtropical North Pacific Ocean near Hawaii (station ALOHA). Deep-Sea Research 40, 
2043- 2060. 
18. 1993 Coble, P. G., C. A. Schultz and K. Mopper. Fluorescence contouring analysis of DOC 
intercalibration experiment samples: a comparison of techniques. Marine Chemistry 41, 
173-178. 
19. 1993 Emerson, S., P. Quay, C. Stump, D. Wilbur and R. Schudlich. Determining primary 
production from the mesoscale oxygen field. ICES Marine Science Symposium 197, 196206. 
20. 1993 Hedges, J. I., B. A. Bergamaschi and R. Benner. Comparative analyses of DOC and 
DON in natural waters. Marine Chemistry 41, 121-134. 
21. 1993 Karl, D. M. Total microbial biomass estimation derived from the measurement of 
particulate adenosine-5'-triphosphate. In: P. F. Kemp, B. F. Sherr, E. B. Sherr and J. J. Cole 
(eds.), Handbook of Methods in Aquatic Microbial Ecology, pp. 359-368. Lewis 
Publishers, Boca Raton. 
22. 1993 Karl, D. M., G. Tien, J. Dore and C. D. Winn. Total dissolved nitrogen and 
phosphorus concentrations at US-JGOFS Station ALOHA: Redfield reconciliation. Marine 
Chemistry 41, 203-208. 
23. 1993 Keeling, C. D. Lecture 2: Surface ocean CO2. NATO ASI Series I(15), 413-429. 
24. 1993 Letelier, R. M., R. R. Bidigare, D. V. Hebel, M. Ondrusek, C. D. Winn and D. M. 
Karl. Temporal variability of the phytoplankton community structure based on pigment 
analyses. Limnology and Oceanography 38, 1420-1437. 
25. 1993 Mopper, K. and C. A. Schultz. Fluorescence as a possible tool for studying the nature 
and water column distribution of DOC components. Marine Chemistry 41, 229- 238. 
26. 1993 Selph, K. E., D. M. Karl and M. R. Landry. Quantification of chemiluminescent DNA 
probes using liquid scintillation counting. Analytical Biochemistry 210, 394-401. 
27. 1993 Sharp, J. H., E. T. Peltzer, M. J. Alperin, G. Cauwet, J. W. Farrington, B. Fry, D. M. 
Karl, J. H. Martin, A. Spitzy, S. Tugrul and C. A. Carlson. Procedures subgroup report. 
Marine Chemistry 41, 37-49. 
28. 1993 Winn, C. D., R. Lukas, D. Hebel, C. Carrillo, R. Letelier and D. M. Karl. The Hawaii 
Ocean Time-series program: Resolving variability in the North Pacific. In: N. Saxena (ed.), 
Recent Advances in Marine Science and Technology, pp. 139-150. Proceedings of the 
Pacific Ocean Congress (PACON). 
29. 1994 Baines, S. B., M. L. Pace and D. M. Karl. Why does the relationship between sinking 
flux and planktonic primary production differ between lakes and oceans? Limnology and 
Oceanography 39, 213-226. 
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30. 1994 Bjorkman, K. and D. M. Karl. Bioavailability of inorganic and organic phosphorus 
compounds to natural assemblages of microorganisms in Hawaiian coastal waters. Marine 
Ecology Progress Series 111, 265-273. 
31. 1994 Campbell, L., H. A. Nolla and D. Vaulot. The importance of Prochlorococcus to 
community structure in the central North Pacific Ocean (Station ALOHA). Limnology and 
Oceanography 39, 954-961. 
32. 1994 Campbell, L., L. P.Shapiro and E. Haugen. Immunochemical characterization of the 
eukaryotic ultraplankton from the Atlantic and Pacific Oceans. Journal of Plankton 
Research 16, 35-51. 
33. 1994 Christian, J. R. and D. M. Karl. Microbial community structure at the U.S.-Joint 
Global Ocean Flux Study Station ALOHA: Inverse methods for estimating biochemical 
indicator ratios. Journal of Geophysical Research 99, 14,269-14,276. 
34. 1994 Karl, D. M. Accurate estimation of microbial loop processes and rates. Microbial 
Ecology 28, 147-150. 
35. 1994 Karl, D. M. and B. D. Tilbrook. Production and transport of methane in oceanic 
particulate organic matter. Nature 368, 732-734. 
36. 1994 Tupas, L. M., B. N. Popp and D. M. Karl. Dissolved organic carbon in oligotrophic 
waters: experiments on sample preservation, storage and analysis. Marine Chemistry 45, 
207- 216. 
37. 1994 Winn, C. D., F. T. Mackenzie, C. J. Carrillo, C. L. Sabine and D. M. Karl. Air- sea 
carbon dioxide exchange in the North Pacific subtropical gyre: Implications for the global 
carbon budget. Global Biogeochemical Cycles 8, 157-163. 
38. 1995 Atkinson, M. A., F. I. M. Thomas, N. Larson, E. Terrill, K. Morita and C. Liu. A 
micro-hole potentiostatic oxygen sensor for oceanic CTDs. Deep-Sea Research 42, 761771. 
39. 1995 Chavez, F. P., K. R. Buck, R. R. Bidigare, D. M. Karl, D. Hebel, M. Latasa, L. 
Campbell and J. Newton. On the chlorophyll a retention properties of glass- fiber GF/F 
filters. Limnology and Oceanography 40, 428-433. 
40. 1995 Christian, J. R. and D. M. Karl. Bacterial ectoenzymes in marine waters: Activity 
ratios and temperature responses in three oceanographic provinces. Limnology and 
Oceanography 40, 1042-1049. 
41. 1995 Christian, J. R. and D. M. Karl. Measuring bacterial ectoenzyme activities in marine 
waters using mercuric chloride as a preservative and a control. Marine Ecology Progress 
Series 123, 217-224. 
42. 1995 Emerson, S., P. D. Quay, C. Stump, D. Wilbur and R. Schudlich. Chemical tracers of 
productivity and respiration in the subtropical Pacific Ocean. Journal of Geophysical 
Research 100, 15,873-15,887. 
43. 1995 Jones, D. R., D. M. Karl and E. A. Laws. DNA:ATP ratios in marine microalgae and 
bacteria: Implications for growth rate estimates based on rates of DNA synthesis. Journal 
of Phycology 31, 215-223. 
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44. 1995 Karl, D. M. A reply to a comment by J. A. McGowan "HOT and the North Pacific 
gyre." Nature 378, 21-22. 
45. 1995 Karl, D. M., R. Letelier, D. Hebel, L. Tupas, J. Dore, J. Christian and C. Winn. 
Ecosystem changes in the North Pacific subtropical gyre attributed to the 1991-92 El Nino. 
Nature 373, 230-234. 
46. 1995 Liu, H., L. Campbell and M. R. Landry. Growth and mortality rates of 
Prochlorococcus and Synechococcus measured with a selective inhibitor technique. Marine 
Ecology Progress Series 116, 277-287. 
47. 1995 Maranger, R. and D. F. Bird. Viral abundance in aquatic systems: a comparison 
between marine and fresh waters. Marine Ecology Progress Series 121, 217-226. 
48. 1995 Sabine, C. L. and F. T. Mackenzie. Bank-derived carbonate sediment transport and 
dissolution in the Hawaiian Archipelago. Aquatic Geochemistry 1, 189-230. 
49. 1995 Sabine, C. L., F. T. Mackenzie, C. Winn and D. M. Karl. Geochemistry of carbon 
dioxide in seawater at the Hawaii Ocean Time-series station, ALOHA. Global 
Biogeochemical Cycles 9, 637-651. 
50. 1995 Sharp, J. H., R. Benner, L. Bennett, C. A. Carlson, S. E. Fitzwater, E. T. Peltzer and 
L. M. Tupas. Analyses of dissolved organic carbon in seawater: the JGOFS EqPac methods 
comparison. Marine Chemistry 48, 91-108. 
51. 1995 Thomas, F. I. M. and M. J. Atkinson. Field calibration of a microhole potentiostatic 
oxygen sensor for oceanic CTDs. Journal of Atmospheric and Oceanic Technology 12, 
390-394. 
52. 1995 Thomas, F. I. M., S. A. McCarthy, J. Bower, S. Krothapalli, M. J. Atkinson and P. 
Flament. Response characteristics of two oxygen sensors for oceanic CTDs. Journal of 
Atmospheric and Oceanic Technology 12, 687-690. 
53. 1995 Tilbrook, B. D. and D. M. Karl. Methane sources, distributions and sinks from 
California coastal waters to the oligotrophic North Pacific gyre. Marine Chemistry 49, 5164. 
54. 1995 Winn, C. D., L. Campbell, J. Christian, R. M. Letelier, D. V. Hebel, J. E. Dore, L. 
Fujieki and D. M. Karl. Seasonal variability in the phytoplankton community of the North 
Pacific subtropical gyre. Global Biogeochemical Cycles 9, 605-620. 
55. 1996 Anbar, A.D., G.J. Wasserburg, D.A. Papanastassiou and P.S. Andersson. Iridium in 
natural waters. Science 273, 1524-1528. 
56. 1996 Andersen, R. A., R. R. Bidigare, M. D. Keller and M. Latasa. A comparison of HPLC 
pigment signatures and electron microscopic observations for oligotrophic waters of the 
North Atlantic and Pacific Oceans. Deep-Sea Research II 43, 517-537. 
57. 1996 Atkinson, M. J., F. I. M. Thomas and N. Larson. Effects of pressure on oxygen 
sensors. Journal of Atmospheric and Oceanic Technology 13, 1267-1274. 
58. 1996 Bingham, F. M. and R. Lukas Seasonal cycles of temperature, salinity and dissolved 
oxygen observed in the Hawaii Ocean Time-series. Deep-Sea Research II 43, 199-213. 
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59. 1996 Campos, M. L. A. M., A. M. Farrenkopf, T. D. Jickells and G. W. Luther III. A 
comparison of dissolved iodine cycling at the Bermuda Atlantic Time-series station and 
Hawaii Ocean Time-series station. Deep-Sea Research II 43, 455-466. 
60. 1996 Chiswell, S. M. Intraseasonal oscillations at Station ALOHA, north of Oahu, Hawaii. 
Deep-Sea Research II 43, 305-319. 
61. 1996 De La Rocha, C. L. and M. A. Brzezinski. Purification, recovery, and laser-driven 
fluorination of silicon from dissolved and particulate silica for the measurement of natural 
stable isotope abundances. Analytical Chemistry 68, 3746-3750. 
62. 1996 Dore, J. E., T. Houlihan, D. V. Hebel, G. Tien, L. Tupas and D. M. Karl. Freezing as 
a method of sample preservation for the analysis of dissolved inorganic nutrients in 
seawater. Marine Chemistry 53, 173-185. 
63. 1996 Dore, J. E. and D. M. Karl. Nitrification in the euphotic zone as a source for nitrite, 
nitrate and nitrous oxide at Station ALOHA. Limnology and Oceanography 41, 1619-1628. 
64. 1996 Dore, J. E. and D. M. Karl. Nitrite distributions and dynamics at Station ALOHA. 
Deep-Sea Research II 43, 385-402. 
65. 1996 Feller, R. J. and D. M. Karl. The National Association of Marine Laboratories: A 
connected web for studying long-term changes in U.S. coastal and marine waters. 
Biological Bulletin 190, 269-277. 
66. 1996 Firing, E. Currents observed north of Oahu during the first five years of HOT. Deep-
Sea Research II 43, 281-303. 
67. 1996 Jones, D. R., D. M. Karl and E. A. Laws. Growth rates and production of 
heterotrophic bacteria and phytoplankton in the North Pacific subtropical gyre. Deep-Sea 
Research I 43, 1567-1580. 
68. 1996 Karl, D. M., J. R. Christian, J. E. Dore, D. V. Hebel, R. M Letelier, L. M. Tupas and 
C. D. Winn. Seasonal and interannual variability in primary production and particle flux at 
Station ALOHA. Deep-Sea Research II 43, 539-568. 
69. 1996 Karl, D. M. and R. Lukas. The Hawaii Ocean Time-series (HOT) program: 
Background, rationale and field implementation. Deep-Sea Research II 43, 129-156. 
70. 1996 Karl, D. M. and A. F. Michaels. Preface: The Hawaiian Ocean Time-series (HOT) 
and Bermuda Atlantic Time-series Study (BATS). Deep-Sea Research II 43, 127-128. 
71. 1996 Kennan, S. C. and R. Lukas. Saline intrusions in the intermediate waters north of 
Oahu, Hawaii. Deep-Sea Research II 43, 215-241. 
72. 1996 Latasa, M., R. R. Bidigare, M. E. Ondrusek and M. C. Kennicutt II. HPLC analysis of 
algal pigments: a comparison exercise among laboratories and recommendations for 
improved analytical performance. Marine Chemistry 51, 315-324. 
73. 1996 Lawson, L. M., E. E. Hofmann and Y. H. Spitz. Time series sampling and data 
assimilation in a simple marine ecosystem model. Deep-Sea Research II 43, 625-651. 
74. 1996 Letelier, R. M., J. E. Dore, C. D. Winn and D. M. Karl. Seasonal and interannual 
variations in photosynthetic carbon assimilation at Station ALOHA. Deep-Sea Research II 
43, 467-490. 
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75. 1996 Letelier, R. M. and D. M. Karl. Role of Trichodesmium spp. in the productivity of the 
subtropical North Pacific Ocean. Marine Ecology Progress Series 133, 263-273. 
76. 1996 Lukas, R. and F. Santiago-Mandujano. Interannual variability of Pacific deep- and 
bottom-waters observed in the Hawaii Ocean Time-series. Deep-Sea Research II 43, 243255. 
77. 1996 Mitchum, G. T. On using satellite altimetric heights to provide a spatial context for 
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conditions of light cycling. Bioprocess and Biosystems Engineering, 27: 163-174. 
186. 2005 Landry, M. R. and A. Calbet. Reality checks on microbial food web interactions in 
dilution experiments: Responses to the comments of Dolan and McKeon. Ocean Science 
1: 39-44. 
187. 2005 Prahl, F. G., B. N. Popp, D. M. Karl and M. A. Sparrow. Ecology and 
biogeochemistry of alkenone production at Station ALOHA. Deep-Sea Research I, 52: 
699-719. 
188. 2006 Brix, H., N. Gruber, D. M. Karl and N. R. Bates. Interannual variability in the 
relationship between primary, net community, and export production in subtropical gyres. 
Deep-Sea Research II, 53: 698-717. 
189. 2006 Church, M. J., H. W. Ducklow and D. M. Karl. Temporal dynamics in heterotrophic 
picoplankton productivity and abundance in the subtropical North Pacific Ocean. Aquatic 
Microbial Ecology, in press. 
190. 2006 Corno, G., R. M. Letelier, M. R. Abbott and D. M. Karl. Assessing primary 
production variability in the North Pacific Subtropical Gyre: A comparison of Fast 
Repitition Rate Fluorometry and 14C measurements. Journal of Phycology, 42: 51-60. 
191. 2006 DeLong, E. F., C. M. Preston, T. Mincer, V. Rich, S. J. Hallam, N.-U. Frigaard, A. 
Martinez, M. B. Sullivan, R. Edwards, B. R. Brito, S. W. Chisholm and D. M. Karl. 
Community genomics among stratified microbial assemblages in the ocean's interior. 
Science, 311: 496-503. 
192. 2006 Huisman, J., N. N. P. Thi, D. M. Karl and B. Sommeijer. Reduced mixing generates 
oscillations and chaos in the deep chlorophyll maximum. Nature, 439: 322-325. 
193. 2006 Huntley, M. E., M. D. G. Lopez, M. Zhou and M.R. Landry. Seasonal dynamics and 
ecosystem impact of mesozooplankton at Station ALOHA, based on OPC measurements. 
Journal Geophysical Research- Oceans, in press. 
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194. 2006 Karl, D. M., R. R. Bidigare, M. J. Church, J. E. Dore, R. M. Letelier, C. Mahaffey 
and J. Zehr. The nitrogen cycle in the North Pacific trades biome: An evolving paradigm. 
In: Nitrogen in the Marine Environment, ed. by D. Capone et al., in press. 
195. 2006 White, A., Y. Spitz, D. M. Karl and R. M. Letelier. Flexible elemental stoichiometry 
in Trichodesmium spp. and its ecological implications. Limnology and Oceanography, 51: 
1777-1790. 
196. 2006 Zehr, J. P., J. P. Montoya, C. Short, A. Hansen, B. D. Jenkins, M. J. Church and D. 
M. Karl. Nitrogenase gene expression in the North Pacific Subtropical Gyre. Limnology 
and Oceanography, in press. 
7.3 Submitted Papers 
1. Corno, G., D. M. Karl, M. J. Church, R. M. Letelier, R. Lukas and M. R. Abbott. The 
impact of climate forcing on ecosystem processes in the North Pacific Subtropical Gyre. 
Submitted to Journal of Geophysical Research. 
2. Corno, G., R. M. Letelier, M. R. Abbott and D. M. Karl. Temporal and vertical variability 
in photosynthesis in the North Pacific Subtropical Gyre. Submitted to Limnology and 
Oceanography. 
3. Hannides, C. C. S., M. R. Landry, C. R. Benitez-nelson, D. M. Karl, R. M. Styles and J. P. 
Montoya. Export stoichiometry and migrant-mediated flux of phosphorus in the North 
Pacific subtropical gyre. Submitted to Nature. 
7.4 Thesis and Dissertations 
1. 1992 Sabine, C. L. Geochemistry of particulate and dissolved inorganic carbon in the 
central North Pacific. Ph.D. Dissertation, May 1992. 
2. 1993 Kennan, S. Variability of the intermediate water north of Oahu. M.S. Thesis, 
December 1993. 
3. 1994 Letelier, R. M. Studies on the ecology of Trichodesmium spp. (Cyanophyceae) in the 
central North Pacific gyre. Ph.D. Dissertation, April 1994. 
4. 1994 Liu, H. B. Growth and mortality rates of Prochlorococcus and Synechococcus 
measured by a selective inhibitor technique. M.S. Thesis, May 1994. 
5. 1995 Dore, J. E. Microbial nitrification in the marine euphotic zone: Rates and 
relationships with nitrite distributions, recycled production and nitrous oxide generation. 
Ph.D. Dissertation, May 1995. 
6. 1995 Christian, J. R. Biochemical mechanisms of bacterial utilization of dissolved and 
particulate organic matter in the upper ocean. Ph.D. Dissertation, December 1995. 
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7. 1995 Troy, P.J. Surface chemistry of solids in the upper ocean. Ph.D. Dissertation, 
University of Hawaii at Manoa, August 1995. 
8. 1997 Thomson-Bulldis, A. A Novel Method for the determination of phosphate and 
dissolved organic phosphorus concentrations in seawater. M.S. Thesis, University of 
Hawaii, December 1997. 
9. 1999 Al-Mutari, H.A. Active export of carbon and nitrogen by diel-migrant zooplankton at 
Station ALOHA. M.S. Thesis, University of Hawaii at Manoa, May 1998. 
10. 1999 Cavender-Bares, K.K. Size distributions, population dynamics, and single-cell 
properties of marine plankton in diverse nutrient environments. Ph.D. Dissertation, 
Massachusetts Institute of Technology, June 1999. 
11. 1999 Bjrkman, K. M. Nutrient dynamics in the North Pacific subtropical gyre: 
phosphorus fluxes in the upper oligotrophic ocean. Ph.D. Dissertation, Stockholm 
University, December 1999. 
12. 2002 Carrillo, C. J. Processes controlling carbon dioxide in seawater. Ph.D. Dissertation, 
University of Hawaii, May 2002. 
13. 2002 Colman A. S. The oxygen isotope composition of dissolved inorganic phosphate and 
the marine phosphorus cycle. Ph.D. Dissertation, Yale University, May 2002. 
14. 2003 Brum, J. A Novel Method for the Determination of Dissolved DNA in Seawater. M.S. 
Thesis, University of Hawaii, May 2003. 
15. 2003 Church, M. J. Microbial dynamics and biogeochemistry in the North Pacific 
Subtropical Gyre. Ph.D. Dissertation, The College of William and Mary in Virginia, March 
2003. 
16. 2003 Hamme, R. C. Applications of neon, nitrogen, argon and oxygen to physical, 
chemical and biological cycles in the ocean. Ph.D. Dissertation, University of Washington, 
June 2003. 
17. 2005 Grabowski, M. Nitrogen Fixation Rates and Controls at Station ALOHA. M.S. 
Thesis, University of Hawaii, September 2005. 
18. 2006 Corno, G. Primary production dynamics in the North Pacific Subtropical Gyre. Ph.D. 
Dissertation, Oregon State University, June 2006. 
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7.5 Data Reports and Manuals 
1. 1990 Karl, D. M., C. D. Winn, D. V. W. Hebel and R. Letelier. Hawaii Ocean Time- series 
Program Field and Laboratory Protocols, September 1990. School of Ocean and Earth 
Science and Technology, Univ. of Hawaii, Honolulu, HI, 72 pp. 
2. 1990 Collins, D. J., W. J. Rhea and A. van Tran. Bio-optical profile data report: HOT- 3. 
National Aeronautics and Space Administration JPL Publ. #90-36. 
3. 1990 Chiswell, S., E. Firing, D. Karl, R. Lukas and C. Winn. Hawaii Ocean Time- series 
Program Data Report 1, 1988-1989. SOEST Tech. Rept. #1, School of Ocean and Earth 
Science and Technology, Univ. of Hawaii, Honolulu, HI, 269 pp. 
4. 1992 Winn, C., S. Chiswell, E. Firing, D. Karl and R. Lukas. Hawaii Ocean Time- series 
Program Data Report 2, 1990. SOEST Tech. Rept. 92-1, School of Ocean and Earth 
Science and Technology, Univ. of Hawaii, Honolulu, HI, 175 pp. 
5. 1993 Winn, C., R. Lukas, D. Karl and E. Firing. Hawaii Ocean Time-series Program Data 
Report 3, 1991. SOEST Tech. Report 93-3, School of Ocean and Earth Science and 
Technology, Univ. of Hawaii, Honolulu, HI, 228 pp. 
6. 1993 Tupas, L., F. Santiago-Mandujano, D. Hebel, R. Lukas, D. Karl and E. Firing. Hawaii 
Ocean Time-series Program Data Report 4, 1992. SOEST Tech. Report 93-14, School of 
Ocean and Earth Science and Technology, Univ. of Hawaii, Honolulu, HI, 248 pp. 
7. 1994 Tupas, L., F. Santiago-Mandujano, D. Hebel, E. Firing, F. Bingham, R. Lukas and D. 
Karl. Hawaii Ocean Time-series Program Data Report 5, 1993. SOEST Tech. Report 94-5, 
School of Ocean and Earth Science and Technology, Univ. of Hawaii, Honolulu, HI, 156 
pp. 
8. 1994 Voss, C. I. and W. W. Wood Synthesis of geochemical, isotopic and groundwater 
modelling analysis to explain regional flow in a coastal aquifer of Southern Oahu, Hawaii. 
In: Mathematical Models and Their Applications to Isotope Studies in Groundwater 
Hydrology, pp. 147-178, International Atomic Energy Agency, Vienna, Austria. 
9. 1995 Tupas, L., F. Santiago-Mandujano, D. Hebel, E. Firing, R. Lukas and D. Karl. Hawaii 
Ocean Time-series Program Data Report 6, 1994. SOEST Tech. Report 95-6, School of 
Ocean and Earth Science and Technology, Univ. of Hawaii, Honolulu, HI, 199 pp. 
10. 1996 Karl, D., L. Tupas, F. Santiago-Mandujano, C. Nosse, D. Hebel, E. Firing and R. 
Lukas. Hawaii Ocean Time-series Program Data Report 7: 1995. SOEST Tech. Report 969, 
School of Ocean and Earth Science and Technology, Univ. of Hawaii, Honolulu, HI, 228 
pp. 
11. 1997 Tupas, L., F. Santiago-Mandujano, D. Hebel, C. Nosse, L. Fujieki, E. Firing, R. 
Lukas and D. Karl. Hawaii Ocean Time-series Program Data Report 8: 1996. SOEST Tech. 
Report 97-7, School of Ocean and Earth Science and Technology, Univ. of Hawaii, 
Honolulu, HI, 296 pp. 
12. 1998 Tupas, L., F. Santiago-Mandujano, D. Hebel, C. Nosse, L. Fujieki, R. Lukas and D. 
Karl. Hawaii Ocean Time-series Program Data Report 9: 1997. SOEST Tech. Report 98-9, 
School of Ocean and Earth Science and Technology, Univ. of Hawaii, Honolulu, HI, 159 
pp. 
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13. 1999 Tupas, L., F. Santiago-Mandujano, C. Nosse, D. Hebel, L. Fujieki, R. Lukas and D. 
Karl. Hawaii Ocean Time-series Program Data Report 10: 1998. SOEST Tech. Report 995, 
School of Ocean and Earth Science and Technology, Univ. of Hawaii, Honolulu, HI, 246 
pp. 
14. 2000 Santiago-Mandujano, F., J. Dore, L. Tupas, D. Hebel, L. Fujieki, R. Lukas and D. 
Karl. Hawaii Ocean Time-series Program Data Report 11: 1999. 
15. 2002 Fujieki, L., F. Santiago-Mandujano, J. Johnson, C. Sheridan, R. Lukas and D. Karl. 
Hawaii Ocean Time-series Program Data Report 12: 2000. 
16. 2004 Fujieki, L., F. Santiago-Mandujano, C. Sheridan, R. Lukas and D. Karl. Hawaii 
Ocean Time-series Program Data Report 13: 2001. 
17. 2005 Fujieki, L., F. Santiago-Mandujano, C. Hannides, R. Lukas and D. Karl. Hawaii 
Ocean Time-series Program Data Report 14: 2002. 
18. 2006 Fujieki, L., F. Santiago-Mandujano, D. Fitzgerald, C. Hannides, R. Lukas and D. 
Karl. Hawaii Ocean Time-series Program Data Report 15: 2003. 
7.6 Newsletters 
1. 1989 Karl, D. M. Hawaiian Ocean Time-series program: It's HOT. GOFS Newsletter 1(2), 13. 
2. 1990 Karl, D. M. HOT Stuff: An update on the Hawaiian Ocean Time-series program. U.S. 
JGOFS Newsletter 2(1), 6,9. 
3. 1990 Karl, David M. HOT Stuff: Rescue at sea. U.S. JGOFS Newsletter 2(2), 8. 
4. 1991 Karl, D. M. HOT Stuff: Retrospect and prospect. U.S. JGOFS Newsletter 2(3), 10. 
5. 1991 Karl, D. M. HOT Stuff: Hectic spring schedule keeps HOT team hustling. U.S. JGOFS 
Newsletter 2(4), 9-10. 
6. 1991 Lukas, R. and S. Chiswell. Submesoscale water mass variations in the salinity 
minimum of the North Pacific. WOCE Notes, 3(1), 6-8. 
7. 1992 Karl, D. M. Hawaii Time-series program: Progress and prospects. U.S. JGOFS 
Newsletter 3(4), 1,15. 
8. 1992 Michaels, A. F. Time-series programs compare results, methods and plans for future. 
U.S. JGOFS Newsletter 4(1), 7,9. 
9. 1992 Winn, C. W. HOT program builds time-series set of carbon measurements for central 
Pacific. U.S. JGOFS Newsletter 4(2), 7. 
10. 1992 Dickey, T. D. Oversight committee reviews time-series programs, issues 
recommendations. U.S. JGOFS Newsletter 4(2), 14-15. 
11. 1992 Firing, E. and P. Hacker. ADCP results from WHP P16/P17. WOCE Notes, 4(3), 6- 12. 
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12. 1992 Chiswell, S. Inverted echo sounders at the WOCE deep-water station. WOCE Notes, 
4(4), 1, 3-6. 
13. 1993 Karl, D. M. HOT Stuff: The five-year perspective. U.S. JGOFS Newsletter 5(1), 6,15. 
14. 1994 Karl, D. M. HOT Stuff: Surprises emerging from five years' worth of data. U.S. JGOFS 
Newsletter 5(4), 9-10. 
15. 1994 Tupas, L. M. Euphotic zone nitrate variability in the central North Pacific gyre at the 
Hawaii Ocean Time-series Station ALOHA. International WOCE Newsletter 17, 21-23. 
16. 1994 Lukas, R. HOT results show interannual variability of Pacific Deep and Bottom waters. 
WOCE Notes 6(2), 1, 3, 14-15. 
17. 1995 Karl, D. M. HOT and COLD: A trapper's tale of two oceans. U.S. JGOFS Newsletter 
6(2): 7, 15. 
18. 1995 Karl, D. M. HOT Stuff: New hypotheses and projects evolve from growing data set. 
U.S. JGOFS Newsletter 7(1): 11. 
19. 1996 Winn, C.D. and P. G. Driscoll. Hawaii Time-series data reveal rising ocean CO2 levels. 
U.S. JGOFS Newsletter 7(4): 7-8. 
20. 1996 Karl, D. M. The Hawaii Ocean Time-series study: Still HOT at 75. U.S. JGOFS 
Newsletter 7(4): 8-9. 
21. 1997 Karl, D.M. HOT scientists deploy mooring at Station ALOHA. US JGOFS Newsletter 
8(2): 4. 
22. 1997 Karl, D.M. Ocean time-series meetings explore new collaboration for future. US 
JGOFS Newsletter 8(3): 15. 
23. 1998 Karl, D.M. The changing sea: Long-term biogeochemical variability in the subtropical 
North pacific. US JGOFS Newsletter 9(3): 7-9. 
24. 1999 Karl, D.M. Wave goodbye: HOT flagship retires from UNOLS fleet. US JGOFS 
Newsletter 10(1): 6. 
7.7 Symposia 
1) Presentations from the "HOT Program: Progress and Prospectus" symposium, 3-4 June 1992, 
East-West Center, Honolulu, HI 
a) Campbell, L. Bacterial numbers by flow cytometry: A new approach 
b) Chiswell, S. Results from the inverted echo sounder network 
c) Christian, J. Biomass closure in the epipelagic zone 
d) Christian, J. Exoenzymatic hydrolysis of high molecular weight organic matter 
e) Dore, J. Annual and short-term variability in the distribution of nitrite at the US-JGOFS 

time-series station ALOHA 
f) Dore, J. and D. Hebel. Low-level nitrate and nitrite above the nutricline at Station 
ALOHA 
g) Firing, E. Ocean currents near ALOHA 


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h) Hebel, D., R. Letelier and J. Dore. Evaluation of the depth dependence and temporal 
variability of primary production at Station ALOHA 
i) Hebel, D., R. Letelier and J. Dore. Past and present dissolved oxygen trends, 
methodology, and quality control during the Hawaii Ocean Time series 
j) Hebel, D. and U. Magaard. Structure and temporal variability in biomass estimates at 
Station ALOHA 
k) Houlihan, T. and D. Hebel. Organic and inorganic nutrients: Water column structure and 

usefulness in time-series analysis 
l) Karl, D. Carbon utilization in the mesopelagic zone: AOU-DOC relationships 
m) Karl, D. HOT/JGOFS program objectives: A brief overview 
n) Karl, D. P-control of N2 fixation: An ecosystem model 
o) Karl, D. Primary production and particle flux 
p) Karl, D. et al. Review and re-assessment of core measurements: Suggestions for 


refinement and improvement 
q) Karl, D. and G. Tien. Low-level SRP above the nutricline at Station ALOHA 
r) Karl, D., L. Tupas, G. Tien and B. Popp. "High-temperature" DOC: Pools and 


implications 
s) Karl, D., K. Yanagi and K. Bjorkman. Composition and turnover of oceanic DOP 
t) Letelier, R. Temporal variability of algal accessory pigments at Station ALOHA: What 

does it tell about the phytoplankton community structure at the DCML?
u) Letelier, R. and D. Hebel. Evaluation of fluorometric and HPLC chlorophyll a 
measurements at Station ALOHA 


v) Letelier, R. and F. Santiago-Mandujano. Wind, sea surface temperature and significant 
wave height records from NDBC buoy #51001 compared to ship observations at Station 
ALOHA 

w) Lukas, R. Water mass variability observed in the Hawaii Ocean Time-series 
x) Sadler, D., C. Winn and C. Carrillo. Time-series measurements of pH: A new approach 

for HOT 
y) Schudlich, R. Upper ocean gas modelling at Station ALOHA 
z) Winn, C. DIC variability 
aa) Winn, C. and C. Carrillo. DIC and alkalinity profiles and elemental ratios 


2) Presentations from the "HOT Golden Anniversary Science Symposium," 16 November 1993, 
East-West Center, Honolulu, HI 
a) Bingham, F. M. The oceanographic context of HOT 
b) Campbell, L., H. Nolla, H. Liu and D. Vaulot. Phytoplankton population dynamics at the 

Hawaii Ocean Time series Station ALOHA 
c) Campbell, L., H. Nolla and D. Vaulot. The importance of Prochlorococcus to community 

structure in the central North Pacific Ocean 
d) Christian, J. Vertical fluxes of carbon and nitrogen at Station ALOHA 
e) Dore, J. Nitrate diffusive flux cannot support new production during quiescent periods at 

Station ALOHA
f) Dore, J. Nitrification in lower euphotic zone at Station ALOHA: Patterns and 
significance


g) Firing, E. The north Hawaiian ridge current and other flows near ALOHA 

h) Hebel, D. Temporal distribution, abundance and variability of suspended particualte 
matter (particulate carbon, nitrogen and phosphorus) at Station ALOHA -- Observations 
of a seasonal cycle 

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i) Karl, D., D. Hebel, L. Tupas, J. Dore and C. Winn. Station ALOHA particle fluxes and 
estimates of export production 
j) Karl, D. M., R. Letelier, L. Tupas, J. Dore, D. Hebel and C. Winn. N2 fixation as a 

contributor to new production at Station ALOHA 
k) Karl, D. M., G. Tien and K. Yanagi. Phosphorus dynamics at Station ALOHA 
l) Kennan, S. C. Possibilities for stirring along the Hawaiian ridge 
m) Krothapalli, S., Y. H. Li and F. T. Mackenzie. What controls the temporal variability of 

carbon flux at Station ALOHA? 
n) Letelier, R. M. Inorganic carbon assimilation at Station ALOHA: Possible evidence of a 
change in carbon fluxes 
o) Letelier, R. M. Spatial and temporal distribution of Trichodesmium sp. at Station 
ALOHA: How important are they? 
p) Liu, H. and L. Campbell. Measurement of growth and mortality rates of Prochlorococcus 
and Synechococcus at Station ALOHA using a new selective inhibitor technique 

q) Lukas, R. and F. Bingham. Annual and interannual variations of hydrographic properties 
observed in the Hawaii Ocean Time-series (HOT) 
r) Lukas, R., F. M. Bingham and A. Mantyla An anomalous cold event in the bottom water 
observed at Station ALOHA 

s) Moyer, C. L., L. Campbell, D. M. Karl and J. Wilcox. Restriction fragment length 
polymorphism (RFLP) and DNA sequence analysis of PCR-generated clones to assess 
diversity of picoeukaryotic algae in the subtropical central North Pacific Ocean (Station 
ALOHA) 

t) Polovina, J. J. and D. R. Kobayashi. HOT and Hawaii's fisheries landings: 

Complementary or independent time-series? 
u) Sadler, D. Time series measurement of pH at Station ALOHA 
v) Smith, C. R., D. J. DeMaster, R. H. Pope, S. P. Garner, D. J. Hoover and S. E. Doan. 

Seabed radionuclides, bioturbation and benthic community structure at the Hawaii Ocean 
Time-series Station ALOHA 
w) Tupas, L. M., B. N. Popp and D. M. Karl. Dissolved organic carbon in oligotrophic 

waters: Experiments on sample preservation, storage and analysis
x) Winn, C. D. Air-sea carbon dioxide exchange at Station ALOHA
y) Yuan, J.and C. I. Measures. Sampling and analysis of dissolved iron


3) Presentations from the "HOT-75 Commemorative Science Symposium," 9 September 1996, 
East-West Center, Honolulu, HI 
a) Atkinson, M. A Potentiostatic, Solid-state Oxygen Sensor for Oceanic CTDs 
b) Bidigare, R., M. Latasa, R. Andersen and M. Keller. A Comparison of HPLC Pigment 
Signatures and Electron Microscopic Observations for Oligotrophic Waters of the North 
Atlantic and North Pacific Oceans 
c) Campbell, L., H. Liu, H. Nolla and D. Vaulot. Annual Variability of Phytoplankton and 
Bacteria in the Subtropical North Pacific Ocean at Station ALOHA during the 19911994 
ENSO Event 
d) Christian, J., M. Lewis and D. Karl. Vertical Fluxes of Carbon, Nitrogen and Phosphorus 
at the US-JGOFS Time-Series Station ALOHA 
e) Dore, J. and D. Karl. Nitrification, New Production and Nitrous Oxide at Station 
ALOHA 
f) Ducklow, H. Joint Global Ocean Flux Study -- Vision and Progress 

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g) Emerson, S., C. Stump and D. Wilber. Inert Gases as Tracers of Diapycnal Mixing in the 
Upper Ocean 

h) Firing, E. Currents in the Vicinity of Station ALOHA: An Update 

i) Fujieki, L. HOT-DOGS: A New Tool for HOT Program Data Base Analysis and 
Presentation 

j) Hebel, D., L. Tupas and D. Karl. The Importance of Organic Exudates in the 
Measurement of Oligotrophic Ocean Primary Productivity 

k) Karl, D., D. Hebel and L. Tupas. Regionalization of Station ALOHA 

l) Karl, D., G. Tien, K. Bjrkman, K. Yanagi, R.Letelier, A. Colman and A. Thomson. The 
"Forgotten" Open Ocean P-Cycle 

m) Karl, D., L. Tupas, D. Hebel, R. Letelier, J. Christian and J. Dore. Station ALOHA N-
Cycle: The Case for N2 Fixation 

n) Landry, M., K. Selph and H. Al-Mutairi. Seasonal and Diurnal Variability of the 
Mesozooplankton Community at Ocean Station ALOHA 

o) Letelier, R. and M. Abbott. Effects of a Subsurface Trichodesmium spp. Bloom on the 
Optical Reflectance Measured in the Upper 150 m of the Water Column in the North 
Pacific Subtropical Gyre 

p) Liu, H., L. Campbell and H. Nolla. Prochlorococcus Growth Rate and Daily Variability 
at Station ALOHA 

q) Lopez, M. and M. Huntley. Particle Concentrations at the Hawaii Ocean Time-series 
Station (Station ALOHA) Measured with an Optical Plankton Counter 

r) Michaels, A. and A. Knap. The Bermuda Atlantic Time-Series Study (BATS): A View 
from the "Other" Ocean 

s) Nolla, H., J. Kirshtein, M. Landry, D. Karl, L. Campbell and D. Pence. Flow Cytometry 
Correction Factors for Enumeration of Heterotrophic Bacteria and Phytoplankton 

t) Quay, P. and H. Anderson. A Dissolved Inorganic Carbon Budget at Station ALOHA 

u) Santiago-Mandujano, F. and R. Lukas. Cold Bottom Water Events Observed in the 
Hawaii Ocean Time-Series: Modelling and Implications for Vertical Mixing 

v) Scharek, R., M. Latasa, D. Karl and R. Bidigare. Vertical Flux of Diatoms at the 
JGOFS/WOCE Station ALOHA 

w) Smith, C., R. Miller, R. Pope and D. DeMaster. Seafloor Inventories of Pb-210, Th-234 
and Benthic Biomass as Proxies for Deep POC Flux: Placing Export Production at the 
HOT Station in a General Oceanic Context 

x) Tien, G., D. Pence and D. Karl. Hydrogen Peroxide Measurements at Station ALOHA 

y) Tupas, L., G. Tien, D. Hebel and D. Karl. Dissolved Organic Carbon Dynamics in the 
Upper Water Column at Station ALOHA 

z) Vink, S., K. Falkner, V. Tersol, J. Yuan and C. Measures. Variations in Iron, Aluminum, 
Beryllium and Barium Concentrations in Surface Waters at Station ALOHA 

aa) Winn, C. Secular Changes in Inorganic Carbon Parameters at HOT and BATS 

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8.0 DATA AVAILABILITY AND DISTRIBUTION 
Data collected by HOT program scientists are made available to the oceanographic 
community in various ways as soon after processing as possible. The complete data set, 
containing data collected since year 1 of the HOT program (1988-89), as well as 2 dbar averaged 
CTD data, are available from a pair of workstations at the University of Hawaii, and may be 
accessed using anonymous File Transer Protocol (FTP) or the World Wide Web (WWW). 

8.1 File Transfer Protocol 
In order to maximize ease of access, the data are in ASCII files. File names are chosen so 
that they may be copied to DOS machines without ambiguity. (DOS users should be aware that 
Unix is case-sensitive, and Unix extensions may be longer than 3 characters.) 

The data are in a subdirectory called /pub/hot. More information about the data base is 
given in several files called Readme.* at this level. The file Readme.first gives general 
information on the data base; we encourage users to read it first. 

The following is an example of how to use FTP to obtain HOT data. The user's 
commands are denoted by bold italicized text. The workstation's Internet address is 
mana.soest.hawaii.edu, or 128.171.154.9 (either address should work). All hydrographic 
information reside at this address. Biogeochemical and optical data are stored at 
ftp://ftp.soest.hawaii.edu/dkarl/hot. 

1. At the Prompt >, type ftp 128.171.154.9 or ftp mana.soest.hawaii.edu. 
2. When asked for your login name, type anonymous. 
3. When asked for a password, type in your e-mail address. 
4. To change to the HOT database, type cd /pub/hot. To view files type ls. A directory of 
files and subdirectories will appear. 
5a. To obtain information about the database type get Readme.first. This will transfer an 
ASCII file to your system. Use any text editor to view it. 

5b. To obtain a list of publications, type cd publication-list then get hotpub.lis. 

5c. To obtain the HOT Field and Laboratory Protocols manual, type cd protocols then get 
1142.asc. 

5d. To obtain CTD data, type cd ctd/hot-#, where # is the HOT cruise of interest, then type 
mget *.ctd to transfer all the cruise CTD files to your system. 

5e. To obtain water column data, type cd water, then get <filename> where the filename is 
hot#.gof (JGOFS data) or hot#.sea (PO data) and # is the HOT cruise of interest. 

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6. To exit type bye. 
7. Biogeochemical and optical parameters are located on another server. At the prompt type 
ftp ftp.soest.hawaii.edu follow steps 2 and 3, then change directories to /dkarl/hot. 
To access hydrographic data from recent cruises (data preliminarily calibrated and 
quality controlled), the user is required to submit a simple registration form available at 
www.soest.hawaii.edu/ HOT_WOCE/regis-form.html. After submitting the registration form, an 
e-mail will be sent to the user with further instructions on how to access the data. 

8.2 World Wide Web 
The Hawaii Ocean Time-series Program maintains a site on the World Wide Web where 
data and information about the program and its activities can easily be accessed over the Internet. 
The address is http://hahana.soest.hawaii.edu/hot/hot.html. This web page is the springboard 
from which the homepages of the Physical Oceanography and Biogeochemistry & Ecology 
components are accessible. The first half of the most recent years hydrographic data is usually 
available by July and the second half by January of the following year with certain quality 
control caveats. All available data are quality controlled by around June of the following year. 
Downloading of data is through FTP but the web pages provide a more detailed means of access. 

8.3 HOT-DOGS 
HOT-DOGS is the acronym for the Hawaii Ocean Time-series Data Organization and 
Graphical System. It's address is http://hahana.soest.hawaii.edu/hot/hot-dogs/interface.html. 
HOT-DOGS is a Matlab based program that displays HOT data in a graphical format as depth 
profiles, time-series or contour plots. In addition to its graphical capabilities, HOT-DOGS 
provides a means of downloading selected data parameters during specific years of the program. 
The user may perform the following: 

 Data Extraction 
Bottle (discrete) 
CTD (continuous) 
Microzooplankton (Nets) 
Particle Flux 
Primary Production 
 Display 
Bottle (discrete) 
CTD (continuous) 
125



HPLC Pigments 
Particle Flux 
Primary Production 
Solar Irradiance 
PRR (Ir)radiance 
TSRB (Ir)radiance 
Inherent Optical Properties 
Fast Repitition Rate Fluorometry 
Underway Measurements 
User Defined 
 Standard Depths (vertical Water-Column) 
Bottle (discrete) 
HPLC Pigments 
Primary Production 
User Defined 
 Time-series 
Bottle (discrete) 
HPLC Pigments 
Macrozooplankton (Nets) 
Particle Flux 
Primary Production 
PRR (Ir)radiance 
User Defined 
 Contour 
Bottle (discrete) 
CTD (continuous) 
HPLC Pigments 
Primary Production 
User Defined 
 Miscellaneous 
Mixed-layer Depth 
126



Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 155 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1a)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1b)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 157 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1c)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 158 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1d)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 159 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1e)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 160 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1f)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 161 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1g)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 162 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1h)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 163 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1i)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 164 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1j)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 165 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1k)
Oxygen ( mol/kg ) 

Pressure ( dbar 
) 
Pressure ( dbar ) 

Station ALOHA HOT 166 

0 


30 

25 

1000 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

3000 

10 

4000 
5 

5000 

0

0 10 20 30 0 100 200 300 
Temperature ( oC ) 


Oxygen ( mol/kg ) 

34 35 36 37 


Salinity 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

0 


30 

25
200



20 

400 

15 

600 

10 

800
5


1000 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34.0 34.5 35.0 35.5 0 100 200 300 
Salinity 


(Text Box comment Figure 6.1.1l)
Oxygen ( mol/kg ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 155 
34 35 36 37 38 
(Text Box comment Figure 6.1.2a)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

34 35 36 37 38 
Salinity 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
(Text Box comment Figure 6.1.2b)

0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 157 
34 35 36 37 38 
(Text Box comment Figure 6.1.2c)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 158 
34 35 36 37 38 
(Text Box comment Figure 6.1.2d)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 159 
34 35 36 37 38 
(Text Box comment Figure 6.1.2e)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 160 
34 35 36 37 38 
(Text Box comment Figure 6.1.2f)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 161 
34 35 36 37 38 
(Text Box comment Figure 6.1.2g)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 162 
34 35 36 37 38 
(Text Box comment Figure 6.1.2h)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 163 
34 35 36 37 38 
(Text Box comment Figure 6.1.2i)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 164 
34 35 36 37 38 
(Text Box comment Figure 6.1.2j)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 165 
34 35 36 37 38 
(Text Box comment Figure 6.1.2k)
Salinity 


0 
200 
400 
600 
800 
1000 
Pressure ( dbar ) 
0 1020304050607080 
Temperature ( oC ) 

0 
200 
400 
600 
800 
1000 
Pressure ( dbar )
Station ALOHA HOT 166 
34 35 36 37 38 
(Text Box comment Figure 6.1.2l)
Salinity 


 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 155 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3a)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 156 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3b)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 157 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3c)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 158 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3d)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 159 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3e)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 160 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3f)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment (g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m3 )
Station ALOHA HOT 161 
Chloropigment (g/l) 


(Text Box comment Figure 6.1.3g)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 162 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3h)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 163 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3i)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 164 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3j)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 165 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3k)

 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
Chloropigment ( g/l) 
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 
200 
150 
100 
50 
0 
Pressure (dbar)
25.5 
25 
24.5 
24 
23.5 
23 
Potential Density (kg/m 3 )
Station ALOHA HOT 166 
Chloropigment ( g/l) 


(Text Box comment Figure 6.1.3l)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 155 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4a)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 156 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4b)

Kahe Pt. HOT 157 

0 


30 

25 

200 


Pressure ( dbar )

Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4c)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 158 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4d)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 159 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4e)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 160 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4f)

Kahe Pt. HOT 161 

0 


30 

25 

200 


Pressure ( dbar )

Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4g)

Kahe Pt. HOT 162 

0 


30 

25 

200 


Pressure ( dbar )

Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4h)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 163 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4i)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 164 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4j)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 165 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4k)

Pressure ( dbar 
) 
Pressure ( dbar ) 

Kahe Pt. HOT 166 

0 


30 

25 

200 


Potential Temperature ( oC 
) 
Potential Temperature ( oC )

20 

15 

10 

800 

5 

1000 
0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 

Kaena Pt. 

0 


30 

25
500



20 

1000 

15 

1500 

10 

2000 
5 

2500 

0

0 10 20 30 34.0 34.5 35.0 35.5 
Temperature ( oC ) 


Salinity 
34 35 36 37 0 100200300 


Salinity 
Oxygen ( mol/kg ) 
-300 -200 -100 0 100 200 300 


Oxygen ( mol/kg ) 
22 24 26 28 

s. ( kg/m3 ) 


(Text Box comment Figure 6.1.4l)

Pressure [dbar] Pressure [dbar] 

0 

-500 
-1000 
-1500 
-2000 
-2500 
-3000 
-3500 
-4000 
-4500 
-5000 

0 

-2500 

-3000 

-3500 

-4000 

-4500 

-5000 

HOT 155-166 WOCE deep casts 


5 1015202530 
Potential Temperature [C] 

HOT 155-166 WOCE deep casts 


1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 
Potential Temperature [C] 


(Text Box comment Figure 6.1.5)

HOT 155-166 WOCE deep casts 

0 
5 
10 
15 
20 
25 
30 
Potential Temperature [C] 
34 34.2 34.4 34.6 34.8 35 35.2 35.4 
Salinity 

HOT 155-166 WOCE deep casts 

34.2 34.3 34.4 34.5 34.6 34.7 34.8 
1 
1.5 
2 
2.5 
3 
3.5 
4 
4.5 
5 
Potential Temperature [C] 
Salinity 


(Text Box comment Figure 6.1.6)

HOT 155-166 WOCE deep casts 

0 
5 
10 
15 
20 
25 
30 
Potential Temperature [C] 
0 50 100 150 200 250 
Oxygen [umol/kg] 

HOT 155-166 WOCE deep casts 

0 20 40 60 80 100 120 140 160 180 200 

1 
1.5 
2 
2.5 
3 
3.5 
4 
4.5 
5 
Potential Temperature [C] 
Oxygen [umol/kg] 


(Text Box comment Figure 6.1.7)

Figure 6.1.8

Figure 6.1.9

Figure 6.1.10

Figure 6.1.11

Figure 6.1.12

Figure 6.1.13

Figure 6.1.14

Figure 6.1.15

Figure 6.1.16

Figure 6.1.17

Figure 6.1.18

Figure 6.1.19

Figure 6.1.20

Figure 6.1.21

Figure 6.1.22

Figure 6.1.23

Dissolved Oxygen (mol/kg) 

[Nitrate+Nitrite] (mol/kg) 

HOT 1-166 Mean Oxygen between Sigma-Theta 27.0 and 27.8 

60 

58 

56 

1990 1995 2000 2005 
Annual Mean 
40.5 

40 

39.5 

1990 1995 2000 2005 
Annual Mean 
HOT 1-123 Mean Soluble Reactive Phosphorus between Sigma-Theta 27.0 and 27.8 

54 

HOT 1-123 Mean [Nitrate+Nitrite] between Sigma-Theta 27.0 and 27.8 

41 

2.86 
2.88 
2.9 
2.92 
2.94 
2.96 
SRP (mol/kg) 
Annual Mean 
1990 1995 2000 2005



(Text Box comment Figure 6.1.24)

s 

. 

Temperature (oC) 

HOT-155 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

25.5 

25 

24.5 

24 


24 

23.8 

23.6 
23.4 
34.6 
34.8 
35 
35.2 
35.4 
Salinity 
20 21 22 23 24 25 
January 2004 (GMT) 


(Text Box comment Figure 6.2.1a)

s 

. 

Temperature (oC) 

34.2 
34.4 
34.6 
34.8 
35 
35.2 
Salinity
HOT-156 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle
26


25.5 
25 
24.5 
24 
23.5 


24 

23.5 
23 

22.5 
23 24 25 26 27 28 
February 2004 (GMT) 


(Text Box comment Figure 6.2.1b)

HOT-157 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

22.5 
23 
23.5 
24 
24.5 
25 
Temperature (o C) 
uncalibrated data 
34 
34.5 
35 
35.5 
Salinity
24.5 

24 

23.5 

23 
18 19 20 21 22 23 


March 2004 (GMT) 

s 

. 


(Text Box comment Figure 6.2.1c)

HOT-158 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

23.5 
24 
24.5 
25 
25.5 
26 
Temperature (o C) 
34.2 
34.4 
34.6 
34.8 
35 
35.2 
Salinity
22.8 
23 
23.2 
23.4 
23.6 
23.8 
s.
19 20 21 22 23 24 
April 2004 (GMT) 


(Text Box comment Figure 6.2.1d)

s 

. 

Temperature (oC) 

34 
34.2 
34.4 
34.6 
34.8 
Salinity
HOT-159 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

27.5 
27 
26.5 
26 
25.5 
25 
23.5 

23 

22.5 
22 
17 18 19 20 21 22 


May 2004 (GMT) 


(Text Box comment Figure 6.2.1e)

s 

. 

Temperature (oC) 

HOT-160 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

27.5 
27 
26.5 
26 
25.5 


23.2 
23 
22.8 
22.6 
22.4 
34.4 
34.5 
34.6 
34.7 
34.8 
Salinity 
14 15 16 17 18 19 
June 2004 (GMT) 


(Text Box comment Figure 6.2.1f)

s. 
SalinityTemperature (oC) 

HOT-161 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

28.5 
28 
27.5 
27 
26.5 
26 
34.9 

34.8 

34.7 

34.6 
34.5 
23 
22.8 
22.6 
22.4 
22.2 
22 
12 13 14 15 
July 2004 (GMT) 


(Text Box comment Figure 6.2.1g)

s 

. 

Temperature (oC) 

34.6 
34.7 
34.8 
34.9 
35 
Salinity
HOT-162 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle
28


27.5 
27 
26.5 
26 
25.5 


23 

22.8 

22.6 
22.4 
22.2 
22 
14 15 16 17 18 19 
August 2004 (GMT) 


(Text Box comment Figure 6.2.1h)

HOT-163 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle 

28.5 
28 
27.5 
27 
34.7 
34.75 
34.8 
34.85 
34.9 
34.95 
35 
Salinity
22.8 

22.6 

22.4 

22.2 
22 
27 28 29 30 1 
September-October 2004 (GMT) 


. 

Temperature (oC) 

s



(Text Box comment Figure 6.2.1i)

s 

. 

Temperature (oC) 

34.6 
34.8 
35 
35.2 
35.4 
Salinity
HOT-164 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle
28


27.5 
27 
26.5 
26 
25.5 


23.4 

23.2 
23 
22.8 
22.6 
22.4 
29 30 31 1 2 
October-November 2004 (GMT) 


(Text Box comment Figure 6.2.1j)

s 

. 

Temperature (oC) 

34.7 
34.8 
34.9 
35 
35.1 
Salinity
HOT-165 Thermosalinograph, o=CTD at 3 dbar, x=salinity bottle
27


26.5 

26 

25.5 


23.4 

23.2 
23 
22.8 
22.6 
22.4 
26 27 28 29 30 1 
November-December 2004 (GMT) 


(Text Box comment Figure 6.2.1k)

s 

. 

Temperature (oC) 

34.6 
34.7 
34.8 
34.9 
35 
Salinity
HOT-166 Thermosalinograph, o=CTD at 8 dbar, x=salinity bottle
26


25.5 

25 

24.5 


23.3 

23.2 

23.1 
23 
22.9 
19 20 21 22 23 24 
December 2004 (GMT) 


(Text Box comment Figure 6.2.1l)

HOT-155 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 
6 
5 
4 
3 
2 
1 
0 


20 21 22 23 24 25 
January 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2a)

HOT-156 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


23 

22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 

157.8 
6 
5 
4 
3 
2 
1 
0 


23 24 25 26 27 28 
February 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2b)

HOT-157 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
20.5 

158.6 

158.4 

158.2 
158 
157.8 

8 


6 
4 
2 
0 


18 19 20 21 22 23 
March 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2c)

HOT-158 Navigation and Ship Speed 

21 
21.5 
22 
22.5 
23 
23.5 
Latitude (N) 
157.9 
158 
158.1 
158.2 
158.3 
158.4 
Longitude (W)
0 
1 
2 
3 
4 
5 
6 
Ship Speed (m/s) 
19 20 21 22 23 24 
April 2004 (GMT) 


(Text Box comment Figure 6.2.2d)

HOT-159 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.6 

158.4 

158.2 
158 
157.8 

8 


6 
4 
2 
0 


17 18 19 20 21 22 
May 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2e)

HOT-160 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 

157.8 
8 
6 
4 
2 
0 


14 15 16 17 18 19 
June 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2f)

HOT-161 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 

157.8 
6 
5 
4 
3 
2 
1 
0 


12 13 14 15 
July 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2g)

HOT-162 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 
6 
5 
4 
3 
2 
1 
0 


14 15 16 17 18 19 
August 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2h)

HOT-163 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 

157.8 
6 
5 
4 
3 
2 
1 
0 


27 28 29 30 1 
September-September 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2i)

HOT-164 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 

157.8 
15 
10 

5 

0 
29 30 31 1 2 


October-October 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2j)

HOT-165 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 

157.8 
6 
5 
4 
3 
2 
1 
0 


26 27 28 29 30 1 
November-December 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2k)

HOT-166 Navigation and Ship Speed 

Latitude (N)

Longitude (W)


22.5 
22 
21.5 
21 
158.4 

158.3 

158.2 

158.1 
158 
157.9 
15 
10 

5 

0 
19 20 21 22 23 24 


December 2004 (GMT) 

Ship Speed (m/s) 


(Text Box comment Figure 6.2.2l)

HOT 155-166 Atmospheric Pressure

 J F M A M J J A S O N D 
2004 

Sea Surface Temperature 

1000 
1005 
1010 
1015 
1020 
1025 
Pressure (mbar) 
22 
23 
24 
25 
26 
27 
28 
29 
30 
Sea Surface Temperature (C) 
J F M A M J J A S O N D


2004



(Text Box comment Figure 6.3.1)

HOT 155-166 Dry Bulb Air Temperature

 J F M A M J J A S O N D 
2004 

Wet Bulb Air Temperature 

25 
24 
23 
22 
21 
20 
19 
18 
17 
J F M A M J J A S O N D 


18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
Dry bulb air temperature (C)
Wet bulb air temperature (
 
C) 

2004



(Text Box comment Figure 6.3.2)

HOT 155-166 SST - Dry Air Temperature

 J F M A M J J A S O N D 
2004 

Relative Humidity 

100 
95 
90 
85 
80 
75 


-1.0 
0.0 
1.0 
2.0 
3.0 
4.0 
5.0 
SST - dry air temperature (C) 
Relative Humidity (%) 


70 
65 
60 

J F M A M J J A S O N D 

2004



(Text Box comment Figure 6.3.3)

19 20 21 22 23 24 25 
5.0 m/s 
HOT 155 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
19 20 21 22 23 24 25 
5.0 m/s 
HOT 155-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
19 20 21 22 23 24 25 
5.0 m/s 
HOT 155 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4a

52 53 54 55 56 57 58 59 60 
5.0 m/s 
HOT 156 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
52 53 54 55 56 57 58 59 60 
5.0 m/s 
HOT 156-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
52 53 54 55 56 57 58 59 60 
5.0 m/s 
HOT 156 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4b

76 77 78 79 80 81 82 83 
5.0 m/s 
HOT 157 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
76 77 78 79 80 81 82 83 
5.0 m/s 
HOT 157-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
76 77 78 79 80 81 82 83 
5.0 m/s 
HOT 157 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4c

107 108 109 110 111 112 113 114 
5.0 m/s 
HOT 158 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
107 108 109 110 111 112 113 114 
5.0 m/s 
HOT 158-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
107 108 109 110 111 112 113 114 
5.0 m/s 
HOT 158 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4d

137 137.5 138 138.5 139 139.5 140 140.5 141 141.5 142 
5.0 m/s 
HOT 159 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
137 137.5 138 138.5 139 139.5 140 140.5 141 141.5 142 
5.0 m/s 
HOT 159-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
Figure 6.3.4e

164 165 166 167 168 169 170 
5.0 m/s 
HOT 160 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
164 165 166 167 168 169 170 
5.0 m/s 
HOT 160-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
164 165 166 167 168 169 170 
5.0 m/s 
HOT 160 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4f

192 192.5 193 193.5 194 194.5 195 195.5 196 
5.0 m/s 
HOT 161 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
192 192.5 193 193.5 194 194.5 195 195.5 196 
5.0 m/s 
HOT 161-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
192 192.5 193 193.5 194 194.5 195 195.5 196 
5.0 m/s 
HOT 161 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4g

225 226 227 228 229 230 231 
5.0 m/s 
HOT 162 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
225 226 227 228 229 230 231 
5.0 m/s 
HOT 162-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
225 226 227 228 229 230 231 
5.0 m/s 
HOT 162 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4h

269 270 271 272 273 274 275 
5.0 m/s 
HOT 163 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
269 270 271 272 273 274 275 
5.0 m/s 
HOT 163-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
269 270 271 272 273 274 275 
5.0 m/s 
HOT 163 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4i

301 302 303 304 305 306 307 
5.0 m/s 
HOT 164 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
301 302 303 304 305 306 307 
5.0 m/s 
HOT 164-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
301 302 303 304 305 306 307 
5.0 m/s 
HOT 164 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4j

329 330 331 332 333 334 335 
5.0 m/s 
HOT 165 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
329 330 331 332 333 334 335 
5.0 m/s 
HOT 165-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
329 330 331 332 333 334 335 
5.0 m/s 
HOT 165 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4k

352 353 354 355 356 357 358 
5.0 m/s 
HOT 166 Shipboard True Winds, Observed 
Julian days from January, 1, 2004 
352 353 354 355 356 357 358 
5.0 m/s 
HOT 166-True Winds, from the continuous record of the ship 
Julian days from January 1, 2004 
352 353 354 355 356 357 358 
5.0 m/s 
HOT 166 - True Winds, buoy data (23 24N, 162 18W) 
Julian days from January 1, 2004 
Figure 6.3.4l

Velocity On Station 

HOT-155 

20.5 21 21.5 22 22.5 23 
2004 Days 
Harmonic Analysis of Velocity 

mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
(Text Box comment Figure 6.4.1a)

54.5 55 55.5 56 56.5 57 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
Velocity On Station 
2004 Days 
Depth (m) 
HOT-156 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
Harmonic Analysis of Velocity 
Depth (m) 
mean 
+ trend 
semidiurnal 
12.42 hours 
diurnal 
24 hours 
Figure 6.4.1b

Velocity On Station 

0 

-50 

-100 

-150 

-200 

-250 

-300 

HOT-158


0.1 m/s 
Depth (m) Depth (m) 

110 110.5 111 111.5 112 112.5 113 113.5 114 
2004 Days 

Harmonic Analysis of Velocity
0


-50 

-100 

-150 

-200 

-250 

-300 

0.1 m/s 
mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
(Text Box comment Figure 6.4.1c)

Velocity On Station 

HOT-159 

138.5 139 139.5 140 140.5 141 
2004 Days 
Harmonic Analysis of Velocity 

mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
(Text Box comment Figure 6.4.1d)

Velocity On Station 

0 

-50 

-100 

-150 

-200 

-250 

-300 

HOT-160


0.1 m/s 
Depth (m) 
Depth (m) 

166 166.5 167 167.5 168 168.5 169 
2004 Days 

Harmonic Analysis of Velocity
0


-50 

-100 

-150 

-200 

-250 

-300 

0.1 m/s 
mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
(Text Box comment Figure 6.4.1e)

Velocity On Station 

0 

-50 

-100 

-150 

-200 

-250 

-300 

HOT-161



Depth (m) 
Depth (m) 

194.7 194.75 194.8 194.85 194.9 194.95 195 195.05 195.1 195.15 195.2 
2004 Days 
Harmonic Analysis of Velocity
0


-50 

-100 

-150 

-200 

-250 

-300 

0.1 m/s 
mean semidiurnal 

+ trend 12.42 hours 
(Text Box comment Figure 6.4.1f)

Velocity On Station 

HOT-162 

227.5 228 228.5 229 229.5 230 230.5 
2004 Days 
Harmonic Analysis of Velocity 

-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
mean semidiurnal diurnal inertial 

+ trend 12.42 hours 24 hours 31 hours 
(Text Box comment Figure 6.4.1g)

Velocity On Station 

HOT-163 

271.5 272 272.5 273 273.5 274 
2004 Days 
Harmonic Analysis of Velocity 

mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
(Text Box comment Figure 6.4.1h)

Velocity On Station 

HOT-164 

303.5 304 304.5 305 305.5 306 
2004 Days 
Harmonic Analysis of Velocity 

mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
(Text Box comment Figure 6.4.1i)

Velocity On Station 

HOT-165 

331.5 332 332.5 333 333.5 334 
2004 Days 
Harmonic Analysis of Velocity 

mean semidiurnal diurnal 

+ trend 12.42 hours 24 hours 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
-300 
-250 
-200 
-150 
-100 
-50 
0 
0.1 m/s 
Depth (m) 
(Text Box comment Figure 6.4.1j)

354 354.5 355 355.5 356 356.5 357 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
Velocity On Station 
2004 Days 
Depth (m) 
HOT-166 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
Harmonic Analysis of Velocity 
Depth (m) 
mean 
+ trend 
semidiurnal 
12.42 hours 
diurnal 
24 hours 
inertial 
31 hours 
Figure 6.4.1k

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-155 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2a

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-156 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2b

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-158 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2c

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-159 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2d

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-160 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2e

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-161 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2f

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-162 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2g

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-163 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2h

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-164 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2i

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-165 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2j

21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Northbound 
Latitude 
Depth (m) 
HOT-166 
21 21.5 22 22.5 23 23.5 
-300 
-250 
-200 
-150 
-100 
-50
0 
0.1 m/s 
158W Southbound 
Latitude 
Depth (m) 
Figure 6.4.2k

(Text Box comment Figure 6.5.1)

HOT 1-166


Dissolved Inorganic CarbonTitration Alkalinity[mol kg-1] (35 ppt) [eq kg-1] (35 ppt) 

2330 
2325 
2320 
2315 
2310 
2305 
2300 
2295 
2290 
2285 
2280 

1990 
1985 
1980 
1975 
1970 
1965 
1960 
1955 
1950 


89 9091 929394959697 98990001020304 
Sampling Date 

HOT 1-166 


89 9091 929394959697 98990001020304 
Sampling Date 


(Text Box comment Figure 6.5.2)

(Text Box comment Figure 6.5.3)

(Text Box comment Figure 6.5.4)

HOT-156 cast 7 HOT-157 cast 7 

150 
100 
50 
0 
P (dbar) 
150 
100 
50 
0 
P (dbar) 
HOT-158 cast 7 HOT-159 cast 7 

150 
100 
50 
0 
P (dbar) 
150 
100 
50 
0 
P (dbar) 
HOT-160 cast 8 HOT-161 cast 3 

150 
100 
50 
0 
P (dbar) 
150 
100 
50 
0 
P (dbar) 
HOT-163 cast 8 HOT-164 cast 7 

150 
100 
50 
0 
P (dbar) 
150 
100 
50 
0 
P (dbar) 
HOT-165 cast 8 HOT-166 cast 9 

150 
100 
50 
0 
P (dbar) 
150 
100 
50 
0 
P (dbar) 
0 5 10152025303540 0 5 10152025303540 
LLN (nmol/kg) LLN (nmol/kg) 


(Text Box comment Figure 6.5.5)

(Text Box comment Figure 6.5.6)

HOT-155 HOT-156 

0 


0 

50

 50


P (dbar) P (dbar) P (dbar)

100


150


P (dbar) P (dbar) P (dbar)

100


150


200 

200 
250 

250 
0 100 200 300 0 100 200 300 
LLP (nmol/kg) LLP (nmol/kg) 

HOT-157 HOT-158
0



0
50


 50


100


100


150


150


200 

200 
250 

250 
0 100 200 300 0 100 200 300 
LLP (nmol/kg) LLP (nmol/kg) 

HOT-159 HOT-160
0



0
50


 50


100


100


150


150


200 

250 

250 
0 100 200 300 0 100 200 300 

LLP (nmol/kg) LLP (nmol/kg) 


(Text Box comment Figure 6.5.7)

HOT-161 HOT-163 

0 


0 

50

 50


P (dbar) P (dbar) P (dbar)

100


150


P (dbar) P (dbar)

100


150


200 

200 
250 

250 
0 100 200 300 0 100 200 300 
LLP (nmol/kg) LLP (nmol/kg) 

HOT-164 HOT-165
0



0
50


 50


100


100


150


150


200 

200 
250 

250 
0 100 200 300 0 100 200 300 
LLP (nmol/kg) LLP (nmol/kg) 
HOT-166 
0 
50100150 

250 
0 100 200 300 


LLP (nmol/kg) 


(Text Box comment Figure 6.5.7 continued)

(Text Box comment Figure 6.5.8)

(Text Box comment Figure 6.5.9)

(Text Box comment Figure 6.5.10)

(Text Box comment Figure 6.5.11)

HOT 1-166 (0-50 dbar means)


1 
1.5 
2 
2.5 
3 
3.5 
4 
4.5 
Particulate Carbon [mol kg-1 ] 
89 909192939495 9697 98990001020304 
Sampling Date 

HOT 1-166 (50-100 dbar means) 

0.5 
1 
1.5 
2 
2.5 
3 
3.5 
Particulate Carbon [mol kg-1 ] 
89 909192939495 9697 98990001020304 
Sampling Date 


(Text Box comment Figure 6.5.12)

(Text Box comment Figure 6.5.13)

HOT 1-166 (0-50 dbar means)


0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
Particulate Nitrogen [mol kg-1 ] 
89 909192939495 9697 98990001020304 
Sampling Date 

HOT 1-166 (50-100 dbar means) 

89 909192939495 9697 98990001020304 
Sampling Date 

0.1 
0.15 
0.2 
0.25 
0.3 
0.35 
0.4 
0.45 
0.5 
0.55 
0.6 
Particulate Nitrogen [mol kg-1 ] 
(Text Box comment Figure 6.5.14)

(Text Box comment Figure 6.5.15)

HOT 1-166 (0-50 dbar means)


5 
10 
15 
20 
25 
30 
35 
Particulate Phosphorus [nmol kg-1 ] 
89 909192939495 9697 98990001020304 
Sampling Date 

HOT 1-166 (50-100 dbar means) 

89 909192939495 9697 98990001020304 
Sampling Date 

0 
5 
10 
15 
20 
25 
30 
35 
Particulate Phosphorus [nmol kg-1 ] 
(Text Box comment Figure 6.5.16)

(Text Box comment Figure 6.5.17)

HOT 79-166 (0-50 dbar means) 

1997 1998 1999 2000 2001 2002 2003 2004 
Sampling Date 

HOT 79-166 (50-100 dbar means) 

0 
20 
40 
60 
80 
100 
120 
140 
160 
180 
200 
Particulate Silica [nmol kg-1] 
0 
5 
10 
15 
20 
25 
30 
35 
40 
45 
50 
Particulate Silica [nmol kg-1 ] 
1997 1998 1999 2000 2001 2002 2003 2004 
Sampling Date 


(Text Box comment Figure 6.5.18)

(Text Box comment Figure 6.5.19)

(Text Box comment Figure 6.5.20)

(Text Box comment Figure 6.5.21)

(Text Box comment Figure 6.5.22)

(Text Box comment Figure 6.5.23)

(Text Box comment Figure 6.5.24)

(Text Box comment Figure 6.5.25)

(Text Box comment Figure 6.5.26)

HOT 1-166


0 
200 
400 
600 
800 
1000 
1200 
Primary Production (mg C m-2 d -1 ) 
89 909192939495 9697 98990001020304 
Sampling Date 

HOT 1-166 

89 909192939495 9697 98990001020304 
Sampling Date 

0 
100 
200 
300 
400 
500 
600 
700 
800 
900 
1000 
Primary Production (mg C m-2 d -1 ) 
(Text Box comment Figure 6.6.1)

(Text Box comment Figure 6.6.2)

0 
10 
20 
30 
40 
50 
60 
70 
89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 
(mg C m-2 d-1) 
Carbon Flux 
HOT 1-166 
0
2
4
6
8 
10 
89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 
(mg N m-2 d-1) 
Nitrogen Flux 
0 
0.2 
0.4 
0.6 
0.8
1 
89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 
(mg P m-2 d-1) 
Phosphorus Flux 
0
2
4
6
8 
10 
89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 
(mg S m-2 d-1) 
Silica Flux 
Sampling Date 
Figure 6.6.3

5 

HOT-155, int = 10.67 [E m-2 d-1]

x 10


Depth (m) 

20 21 22 23 24 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1a)

5 

HOT-156, int = 20.70 [E m-2 d-1]

x 10


Depth (m) 

54 55 56 57 58 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1b)

5 

HOT-157, int = 41.42 [E m-2 d-1]

x 10


Depth (m) 

78 79 80 81 82 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1c)

5 

HOT-158, int = 54.01 [E m-2 d-1]

x 10


Depth (m) 

110 111 112 113 114 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1d)

5 

HOT-159, int = 56.81 [E m-2 d-1]

x 10


Depth (m) 

138 139 140 141 142 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1e)

5 

HOT-160

x 10


Depth (m) 

166 167 168 169 170 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1f)

5 

HOT-161

x 10


Depth (m) 

194 195 196 197 198 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1g)

5 

HOT-162, int = 50.49 [E m-2 d-1]

x 10


Depth (m) 

227 228 229 230 231 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1h)

5 

HOT-163, int = 42.36 [E m-2 d-1]

x 10


Depth (m) 

271 272 273 274 275 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1i)

5 

HOT-164, int = 24.85 [E m-2 d-1]

x 10


Depth (m) 

304 305 306 307 308 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1j)

5 

HOT-165, int = 24.28 [E m-2 d-1]

x 10


Depth (m) 

331 332 333 334 335 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1k)

5 

HOT-166, int = 17.12 [E m-2 d-1]

x 10


Depth (m) 

354 355 356 357 358 

Julian Day 

0 

0 

25 

25 

50 

50 

75 

75 

0 
5 
10 
15 
Incident Irradiance (E m -2 s-1) 
Depth (m)

100


100


125 

125 

150 

150 

175 

175 

200 

200 

0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 
PAR (E cm-2 s -1) K (m-1)
a PAR


(Text Box comment Figure 6.7.1l)

HOT 90-166 1% Light Level


125 
120 
115 
110 
105 
100 
95 
90 
85 
80 
106.5 mDepth [m] 
J A JO J A J O J A JO J A JO J A JO J A JO J A JO 
1998 1999 2000 2001 2002 2003 2004 
HOT 90-166 (100-150 m means) 

0.035 
0.04 
0.045 
0.05 
0.055 
0.0438 m-1 
K 
PAR 
[m -1 ] 
J A JO J A J O J A JO J A JO J A JO J A JO J A JO 
1998 1999 2000 2001 2002 2003 2004 
Sampling Date 


(Text Box comment Figure 6.7.2)

Pressure (dbar) 

HOT-145 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3a)

Pressure (dbar) 

HOT-146 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3b)

Pressure (dbar) 

HOT-147 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3c)

Pressure (dbar) 

HOT-148 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3d)

Pressure (dbar) 

HOT-149 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3e)

Pressure (dbar) 

HOT-150 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3f)

Pressure (dbar) 

HOT-151 

0 

0 


0 

20 

20 

20 

40 

40 

40 

60 

60 

60 

80 

80 

80 

100 

100 

100 

120 

120 

120 

140 

140 

140 

160 

160 

160 

180 

180 

180 

200 

200 

200 

0 0.5 1 0 10203040 0 0.2 0.4 0.6 
FV/FM Alpha (g C mol photon-1 m2 g Chl a-1) FRRF-PP (mg C m-3 hr-1) 
(Text Box comment Figure 6.7.3g)

Depth (m) Depth (m) Depth (m) 

HOT-156 HOT-157 

0 


0 

50

 50


100


Depth (m) Depth (m) Depth (m)

100


150 

150 

200 200 
0 5100 510 
Cell #/ml x 105 Cell #/ml x 105 

HOT-158 HOT-159
0



0 

50

 50


100


100


150 

150 

200 200 
0 5100 510 
Cell #/ml x 105 Cell #/ml x 105 

HOT-160 HOT-162
0



0 

50

 50


100


100


150 

150 

200 

200 
0 5100 510 

Cell #/ml x 105 Cell #/ml x 105 


(Text Box comment Figure 6.8.1)

Depth (m) Depth (m) 

HOT-163 HOT-164 

0 


0 

50

 50


100


Depth (m) Depth (m)

100


150 

150 

200 200 
0 5100 510 
Cell #/ml x 105 Cell #/ml x 105 

HOT-165 HOT-166
0



0 

50

 50


100


100


150 

150 

200 

200 
0 5100 510 

Cell #/ml x 105 Cell #/ml x 105 


(Text Box comment Figure 6.8.1 continued)

(Text Box comment Figure 6.8.2)

Depth (m) Depth (m) Depth (m) 

HOT-156 HOT-157 

0 


0 

50

 50


100


Depth (m) Depth (m) Depth (m)

100


150 

200 200 
0 5000 10000 0 5000 10000 
Cell #/ml Cell #/ml 

HOT-158 HOT-159
0



0 

50

 50


100


100


150 

150 

200 200 
0 5000 10000 0 5000 10000 
Cell #/ml Cell #/ml 

HOT-160 HOT-162
0



0 

50

 50


100


100


150 

200 

200 
0 5000 10000 0 5000 10000 

Cell #/ml Cell #/ml 


(Text Box comment Figure 6.8.3)

Depth (m) Depth (m) 

HOT-163 HOT-164 

0 


0 

50

 50


100


Depth (m) Depth (m)

100


150 

200 200 
0 5000 10000 0 5000 10000 
Cell #/ml Cell #/ml 

HOT-165 HOT-166
0



0 

50

 50


100


100


150 

150 

200 

200 
0 5000 10000 0 5000 10000 

Cell #/ml Cell #/ml 


(Text Box comment Figure 6.8.3 continued)

(Text Box comment Figure 6.8.4)

Year 16 (2004) HOT Zooplankton Dry Weight Biomass


154 156 158 160 162 164 166 

HOT Cruise Number 

Year 16 (2004) HOT Zooplankton Wet Weight Biomass 

0 
1 
2 
3 
DAY 
NIGHTDry Weight Biomass (g DW m-2 )
0 
6 
12 
18 
24 
DAY 
NIGHTWet Weight Biomass (g WW m-2 ) 
154 156 158 160 162 164 

166 


(Text Box comment Figure 6.9.1)
HOT Cruise Number 


