#TEMPORARY ACCESSION NUMBER:
#ACCESSION NUMBER:

#CONTRIBUTOR:
Patrick Caldwell

#CONTRIBUTOR INSTITUTION:
NOAA/NESDIS/NODC/NCDDC
Hawaii Liaison Office
National Coastal Data Development Center
National Oceanic and Atmospheric Administration
1000 Pope Road, MSB 316
University of Hawaii at Manoa
Honolulu, Hawaii 96822
Phone: 808-956-4105
Fax: 808-956-2352
Email: patrick.caldwell@noaa.gov

#ORIGINATOR:
same

#ORIGINATOR INSTITUTION:
same

#TITLE:
Goddard and Caldwell Oahu, Hawaii Surf Observation Dataset
for 1968-2004.

#ABSTRACT: 
Surf reports are typically made several times per day at select
locations around Oahu, primarily by Honolulu City and County lifeguards 
and the Surf News Network, Inc.   Wave heights are reported in Hawaii Scale 
Feet, which systematically underestimates breaker size by as much as one-half.  
Although exactly when and why this tendency originated is highly disputed, 
it became  the primary means of communicating surf size by the late 1960s.
From publicly available surf reports and other notes from reputable surfers,
Mr. Larry Goddard logged heights from 1968 through September 1987 and Mr. 
Patrick Caldwell has done similarly from September 1987 to 2004.  The 
caretakers of the dataset typically cross-check observations among the 
various reporters for quality control.  The daily value in the GC set represents 
the upper end of the reported height range, which is roughly equivalent 
to H1/10, for the observing time and location with the highest breakers
along a given coast facing a similar direction.  For the north shore, 
most observations are taken at Sunset Point, which is usually one of 
the areas of highest surf under the dominant northwest swells.
For days of extreme surf with heights greater than 15 HSF, visual 
observations are reported from Waimea Bay, where breakers are closer 
to shore.  For the south shores, Ala Moana is usually the reporting site.
Observations from the west and east side of Oahu have also been recorded 
although these reports are of lower quality. Comparisons of the GC database 
to 1981-2002 data from NOAA buoy 51001, which is located roughly 400 km 
west-northwest of Oahu, show the north shore surf observations are temporally 
consistent with the shoaling-only, buoy-estimated breaker heights and have 
an uncertainty of 10 to 15% of the surf height. 

#PURPOSE: 
To better understand wave height variability 

#PROJECT:
Oahu Surf Observation Database

#LOCATION EXTREMES:
SOUTHERNMOST LATITUDE: 21.257
SOUTHERNMOST LATITUDE HEMISPHERE: N
NORTHERNMOST LATITUDE: 21.692
NORTHERNMOST LATITUDE HEMISPHERE: N
WESTERNMOST LONGITUDE: 158.222
WESTERNMOST LONGITUDE HEMISPHERE: W 
EASTERNMOST LONGITUDE: 157.662
EASTERNMOST LONGITUDE HEMISPHERE: W  

#LOCATION KEYWORDS: 
North Pacific, Hawaii, Oahu, Waimea Bay, Sunset Point, Makaha,
Maili, Ala Moana, Diamond Head, Makapuu, North Beach

#SAMPLING STATIONS: 
see ../../data/oahu_map.jpg

#BEGIN AND END DATES: 
19680801 - 20040930

#SAMPLING PERIODS:
Visual surf observations are made several times daily,
nominally at 7AM, noon, and 3PM.  The highest reporting
location for a given coast for the time of day of highest
waves is recorded as the daily value in the database.

#PARAMETERS: 
surf height

#METHODOLOGY:
Surf Observations
=================
With the growth of surfing in the 1960s on the north shore, Oahu, came 
routine observations made by surfers, and later in the 1970s, by 
lifeguards and commercial surf report ventures.  Observations were 
reported in Hawaii Scale Feet (HSF). 
 
Observations are reported as a height range.  Observers ignore the 
smaller waves.  As a simplified example, assume a given day has 
dominant wave energy in the 14-17 second wave period range with 
negligible energy outside this band.  Assume five waves catch the 
eye of an observer every four minutes, or 100 waves every 80 minutes.  
This takes into account the time periods of varying length without 
waves arriving.  The upper end of the reporting range is approximately
equivalent to the H1/10, the average of the highest 10 waves, which if 
evenly distributed in time, would occur every 8 minutes.  The lower 
end of the observing range is near the H1/3, or the average of the 
highest 1/3 waves, which if evenly distributed in time, would occur 
every 3 minutes.  The highest wave over this nominal 80-minute period 
with 100 waves, or H1/100, would be equivalent to the observers use 
of occasional heights in their reports.

A digital database of surf observations, referred to as the 
Goddard-Caldwell (GC) set, dates back to August 1968 for the north 
shore, and to March 1972 for the south shore of Oahu.  It is described 
in more detail in Caldwell (2005).  Data are recorded in HSF.  The daily 
values in the GC database refer to the surfing location along the given 
coast with the highest reported breakers.  For the north shore, most 
observations are taken at Sunset Point, which is usually one of the 
highest surf spots along the coast under the dominant northwest swell 
direction.  Under north swell, if reports were available from Laniakea,
which can be bigger than Sunset, then those were used in the GC set.  
For days of extreme surf with heights greater than roughly 
15 HSF, visual observations are reported at Waimea Bay, where breakers 
are much closer to shore relative to most of the north shore, which is 
fringed with offshore reefs.  The surf reports are typically made 
several times per day.  The daily value in the GC set represents the 
upper end of the reported height range for the observing time with the 
highest breakers.  This number aims to be equivalent to H1/10.  Comparisons 
of the GC database to 1981-2002 data from NOAA buoy 51001, which is 
located roughly 400 km west-northwest of Oahu, show the surf observations 
are temporally consistent with the shoaling-only, buoy-estimated breaker 
heights and have an uncertainty of 10 to 15% of the surf 
height (Caldwell, 2005). 

Mr. Larry Goddard maintained the database for the North Shore from 
1968-9/1987 and the south shore (Ala Moana) from 1972-7/1987.  Many 
observations were his own, but he also received help from reputable 
surfers such as Randy Rarick, Peter Coles, Bernie Baker, and Lt. Benson.
Mr. Goddard assumed the lifeguards underestimate the surf by roughly 15% 
when the surf is roughly double the size of a surfer up to the levels when 
Sunset Beach is no longer surfable (15 Hsf).  Thus the following back 
adjustment was made to the Goddard years (1968-8/1987): for surf observations
between 5 and 9', 1' was subtracted and for values between 10 and 15', 2' was 
subtracted.  For south shore observations, if a report was not available
from Ala Moana, and Mr. Goddard was at home near Maili Point on the 
west side of Oahu, then Maili was used as a proxy for Ala Moana, which
has similar swell exposure and refractive characteristics.

Mr. Caldwell began a digital archive of surf observations, coincidently, when 
Mr. Goddard moved to the mainland and discontinued his set.  The Caldwell set 
from 1987 onward considers the primary source as the Oahu lifeguard and the 
Surf News Network, Inc. reports, unless more reliable information was provided 
via a network of surfing friends. The data quality should be higher starting 
in 1999 due to the availability of Internet cameras at key surf locations. 
The cameras also provided late day reports under rising swell conditions.

The wave direction data began in 1990 based on personal knowledge of Mr. Patrick
Caldwell, who has studied the daily weather maps in preparation of surf 
forecasts. Another technique used was noting the swell sizes on the various 
sides of the island.  For instance, if Makaha is 8', Sunset is 10', and 
N.Beach is 2', then the direction is obviously dominated by NW component. Since 
12/2001, a directional buoy near Waimea, Oahu has improved the wave direction 
information.

For the Windward Surf Index, reports from North Beach on the Kaneohe Marine 
Corp Base Hawaii were used until 1995 until it was discontinued by the Oahu 
lifeguard reporting system. Since then, Makapuu has been the primary reporting 
site, although Mr. Caldwell lives in Kailua Hawaii and has been able to fine 
tune the estimates personally.  The windward index includes both trade wind 
energy as well as any long period swell from North Pacific sources.  Due to 
potential for large gradients in size along the windward coast during the arrival
of long period energy, especially if the direction requires refraction around 
Kahuku Point, the Windward Surf Index is of less quality.  Less confidence
is also given to reports from Makaha on the west side.  For those wanting
to research windswell for Windward Oahu, the historic buoy at Makapuu is the 
best option.  These datasets are archived at NODC under Accession Numbers:
9400105, 950087, 9600143, 9600154, and 9700155. 

Wind data are a ballpark estimate of open ocean areas, independent of island 
influence.  Usually, the Bellows or Kahuku anemometers are used as a reference
during trade wind events, and Honolulu airport under S to SW wind conditions.
Use at your discretion.  It is highly recommended that research not
be performed on these wind data.  High quality wind data sets from select
locations in Hawaii can be obtained from the National Climatic Data Center.
 
Translation from Hawaii Scale to Trough-to-Crest Heights.
 
A breaker or surf is defined at the moment in time when some portion of 
the front face of a wave becomes vertical and unstable due to a decrease 
in water depth.  The trough to crest surf height is defined as the vertical 
distance between the crest and the preceding trough at the moment and 
location along the wave front of highest cresting, which has been shown 
in models and observations to be at the time and location of breaking.  For 
locations with high refraction, such as Sunset Point, where most of the 
visual observations are made, the breaker often forms an A-shape.  The 
trough to crest height refers to the center of the A, i.e., the point 
along the wave front with the highest height.
 
The translation (Caldwell and Aucan, 2004) of HSF to trough-to-crest heights 
is a factor of two within the 10-20% margin of error for the full range of 
breaker sizes encountered in Hawaii.  This assumes the height is defined as 
the highest height reached in the vertical from the trough to crest at any point 
along the wave front during breaking and zones of high refraction (outer reefs) 
are included for extreme days when Waimea Bay was the reporting location.  
The HSF, or simply dividing trough to crest height by two, has been adopted 
by other big wave enthusiasts around the globe as seen in pictures and 
dialogue from extreme surf contests in California, Peru, and South Africa.  
It is important for scientists and the general public to understand this 
relationship for utilizing surf observations reported in HSF.

Note, the Goddard-Caldwell database remains in HSF.

Acknowledgements
Thanks are given to the surf observers-- lifeguards of the City and County of 
Honolulu and employees of the Surf News Network.  Deep appreciation is given to 
Mr. Larry Goddard for sharing his digital database of surf observations.  For 
his set of data, thanks go out to the various lifeguard reporters and reputable 
surfers: Randy Rarick, Peter Cole, Bernie Baker, and Albert Benson.  For the 
Caldwell set, thanks are given to Garret McNamara, Ian Masterson, Kaleo Ahina, 
Robert Yonover, and Clark Abbey for surf information which was used in cross 
checking the lifeguard reports.  While the author was away from the island, 
various students and staff at the University of Hawaii and Windward Community 
College Surf Science and Technology class have logged daily reports, a few of 
which include: Ian Masterson, Kaleo Ahina, Shaun Johnston, Eric Grossman, 
Jerome Aucan, Yvonne Firing, Kimball Millikan, and Robert Burke.  Great thanks 
go out to all these individuals.  For access to the digital cameras, appreciation 
is given to Surfline, Inc. (www.surfline.com), and for daily surf notes and 
pictures, thanks are extended to Jamie Ballenger (www.hawaiianwatershots.com) and 
Claudia Ferrari (www.claudiaferrari.com/news.htm).

#INSTRUMENT TYPES:
visual observations

#REFERENCES:
Caldwell, P. and J.Aucan, 2004: Translation of surf observations from Hawaii 
scale to trough to crest heights based on photographic evidence. Poster.  8th 
International Workshop on Wave Hindcasting and Forecasting,  North Shore, 
Oahu, Hawaii, November 2004.

Caldwell, P. and J.Aucan, 2004:  AN EMPIRICAL METHOD FOR ESTIMATING SURF 
HEIGHTS FROM DEEP WATER SIGNIFICANT WAVE HEIGHTS AND PEAK PERIODS IN 
COASTAL ZONES WITH NARROW SHELVES, STEEP BOTTOM SLOPES, AND HIGH 
REFRACTION. 8th International Workshop on Wave Hindcasting and Forecasting,  
North Shore, Oahu, Hawaii, November 2004.

Caldwell, P., 2005: Validity of North Shore, Oahu, Hawaiian Islands surf 
observations. Journal of Coastal Research, 21(1), 2005.

#SUBMITTING MEDIUM:
file copy

#FILE FORMATS: 
Files are stored in directory ../../data
File names: oahuyyyy.dat, where yyyy = year

Surf Heights given in Hawaii Scale Feet.  Trough-to-Crest heights
are double the Hawaii Scale Feet heights within the 10-20%
margin of error.

format layout, columns as:

yyyy mm dd nshor wshor almo dh  winw  wspd wdir nsd ssd
2000  1  1    8    4    1    2    3    2   17   15  999
2000  1  2    5    2    1    2    2    2   17   15  999
2000  1  3    4    2    1    2    2    2   17   15  999

nshor (North Shore, Oahu, mostly Sunset until > 15', then Waimea)
wshor (Makaha)
almo (South Shore, Oahu, Ala Moana Bowls)
dh (Diamond Head)
winw (Windward Oahu (east side) index)
wspd (wind speed in beaufort for open waters)
wdir (wind direction, coded 1=N 2=NNE 3=NE, etc ... 16=NNW
      17:light and variable)
nsd (north shore wave direction as above)
ssd (south shore direction) note for swell directions,  18:mixed
     usually only the dominant direction is given, ignoring mixed
     conditions, which happen commonly

missing data flag for all fields: 999

#DATASET SIZE:
868 Kbytes 

#NUMBER OF DATA UNITS:
5 sites

#MISCELLANEOUS:
Related datasets at NODC:

NODC Accession Number
0000165                       Goddard/Coles North Shore Dataset*
0000274                       Goddard South Shore Dataset*
                             *(same as provided here except the
                               Goddard-Caldwell set (this set) has
                               applied an adjustment for data between
                               5 and 15 HSF for 1968-8/1987). 
xxxxxxx                       Photographs used to translate Hawaii
                              Scale Feet to Trough-to-Crest heights
                              (submitted to NODC Fall 2004).

