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1. Research Cruises
FY Cruise Name Observation Term Data 1990 NH90-3 August 22 to October 15, 1990 none
1991 NH91-2 August 9 to October 7, 1991 none
1992 NH92-1 April 15 to June 13, 1992 none
NH92-2 August 7 to October 5,1992 include
1993 NH93-1 April 13 to June 11,1993 include
NH93-2 August 7 to October 5,1993 include
1994 NH94-1 April 13 to June 11,1994 include
NH94-2 August 8 to October 6,1994 include
1995 NH95-1 April 14 to June 12,1995 include
NH95-2 August 7 to October 5,1995 include
2. Hydrographic data measurement and processing
(1) Sampling
(2) Measurements and Analyses
(3) Quality Assurance and Quality Control Procedures
All the hydrographic data and CTD data
of 1990 to 1995 fiscal year have been subjected to well quality control. This work was
carried out by Data Quality Control Working Group (Leader:H.Tsubota) in NOPACCS Exective
Committee. Members of Working Group were listed in "5.Address" of this Data Set.
The working group has eventually concluded that hydrographic data and CTD data of 7
cruises after the second cruise of 1992 should be opened through JODC, but not the others,
those of 1990 to the first cruise of 1992, becouse of poor precision.
In the hydrographic data sheet,
significant figure for each item was decided based on the analytical precision which was
obtained by replicate analyses of the determinant of the same sample and replicate
samples, and through the intercomparison between leg and leg in a cruise and between
cruise and cruise. Quality assurance of data obtained was conducted based on the
precision. Replicate determinations and samples with too much dispersion have been
thrown out.
To estimate the accuracy of data, the following
three ways were taken : The first one was to participate in an intercalibration workshop.
The second way was to use the common standard materials and to acquire certified reference
materials. The third was to repeat the observations in the deep ocean. It was thought that
the deep layer in the mid ocean is so stable as might be possible to identify the
analytical results. repeat observations at the fixed station were carried out every
cruise. The point of 30N, 175E was selected for this purpose. The reasons were that it
was rather near point from Japan as it was not winding course to stop at this point, and
that the depth ca. 5400m might be enough to compare analytical results. When the
analytical results, for examples, nutrient concentrations were plotted against depth the
distribution patterns did not agree with the distributions of other cruise, but plotting
against ΠΖ gave identical distributions.
For analytical quality control the following
procedures were employed : To confirm water sampling, the bottle salinity was compared
with CTD salinity by referring CTD record. Was there any sharp variation or jump on the
record ? To confirm DO data, vertical distribution pattern was compare with CTDO record.
Sudden change of titration-DO data was checked on the record, because the distribution
pattern might be acceptable although the accuracy of DO sensor were poor. DO/Ζ-plot
was very effective. To confirm (NO3+NO2) and PO4,
N/P-plot was generally more sensitive than their vertical distribution of N/P ratios.
N/Ζand P/Ζ-plots were also available. For the deeper layer than DO minimum layer, N/DO-
and P/DO-plots were also used to confirm these data. And, to confirm Si data, Si/Ζ-plot
was applied adding to the vertical distribution.
All of the hydrographic data were qualified
with such the procedures, and outliers have been thrown out. Doubtful data still remained
were flagged on the Hydrographic Data Sheet. These Data Sheets have been sent to JODC.
| Item | Units | Significant figures |
|---|---|---|
| Pressure | 10E^4 Pa (db) | One decimal place |
| Water temperature | Centigrade | Four decimal places |
| Salinity | - | Four decimal places |
| Dissolved Oxygen | micromole per kilogram | Four digits and one decimal place |
| Phosphate | micromole per kilogram | Three digits and two decimal places |
| Silicate | micromole per kilogram | Three digits and one decimal places |
| Nitrite | micromole per kilogram | Two digits and two decimal places |
| Nitrate and Nitrite | micromole per kilogram | Three digits and two decimal places |
| Total alkalinity | micromole per kilogram | Four digits and an integer place |
| pH | - | Three decimal places |
| Total carbonate content | micromole per kilogram | Four digits and an integer place |
| Chlorophyll-a | microgram per liter | Two digits and three decimal places |
(4) Notes
(1) Definition of Data File Name
File name was consist of four information, observed year, cruise number, observation layer and station number. As regards the file names of each cruise, please refer to text.file named FILENAME.TXT in the CTD data directories of each cruise.
In regard of the position and date of CTD observation , there are indicated at HYDROGRAPHIC DATA directories of each cruise.
(2) Data Procedure
a. Data acquisition
CTD observation was used the CTD made by SEA-BIRD ELECTORONICS, INC.( the more detail of CTD instrument was described at text.file METHO***.ENG located in the HYDROGRAPHIC DATA directory.). The CTD prove was downed at 0.5m/sec speed at the observation.
CTD observed raw data was obtained 24 times every one second at the Sallow layer (o to 300m depth), and 6 times every one second at the Middle and Deep layer (0 to 3000m and 0 to bottom), and then was processed following steps to take average data every one db.
b. Data Processing
There are indicated CTD Processing as followings;
[ DATCNV ] ; to convert raw data recorded by frequency to Engineering units.
[ ALIGNCTD ] ; to correct the response rag between Pressure sensor and Temperature / Conductivity sensor.
SBE911plus is a present used CTD, has a correcting function of Temp. and Con. sensor by hardware and software both. Therefore, this process was processed with time rag 0.
[ LOOPEDIT ] ; to eliminate the data obtained at the slow down speed of CTD prove.
The data obtained with CTD prove down speed less than 0.3m/s was eliminated.
[ BINAVE ] ; to average every one db, for example, the value at 30 db is the average value of more than 29.5 db, and less than 30.5db.
[ DERIVE ] ; to calculate salinity.
[ ASCIIOUT ] ; to omit unnecessary data , and then to put out as text file.
c. Calibration of sensor
- Temperature and Conductivity sensors were checked at National Oceanographic and Atmospheric Administration(NOAA) through SEA-BIRD ELECTRONICS,INC. within one year before research cruise, and also within 3 months after research cruise.
- The correction based on the check at NOAA was not done, because there were not significant difference between before and after check.
- The correction based on the compare check between CTD salinity data and Autosal data was not done, because the compare check were brought good results, at almost of cases the correlation factors more than 0.99 were obtained.
4. POC,PON data measurement and processing
(1) Definition of File Name
File name was consist of observed year, cruise number and observation layer. All file names of NOPACCS's cruises were indicated in Table 1.
(2) Data Description
a. Sampling
Sampling on Shallow Layer (0 to 300m) were operated using the single cast which separated from other HYDROGRAPHIC observation items, but sampling on middle and deep layer were operated using the same cast with other HYDROGRAPHIC observation items. In regard to the methods, please refer to the description of HYDROGRAPHIC DATA because the methods are same as HYDROGRAPHIC DATA.
b. Measurements and Analysis
(a) Ship position (Latitude, Longitude)
(b) Sampling depth (P or Depth), Water temperature (T)
(c) Salinity (S)
The mesurement and analysis of above items are same as HYDROGRAPHIC DATA, so please refer them. However,the salinity on Shallow layer was adopted the value of CTD, which is the same method of water temperature.
(d) POC, PON
6-7 liter of seawater was filtered by a 25mm GF/F filter, which was previously treated by combustion for 4hr. at 450C, and the filter was preserved in a freezer. POC and PON were measured with Perkin-Elmer PE2400CHN, AD-6.
(3) Data processing
Each unit and significant figure were following,
Item Unit significant figure Pressure
10E^4 Pa (db)
One decimal place Temperature
Centigrade
Surface: one decimal places
Shallow: Four decimal places
Middle: Two decimal placesSalinity
-
Four decimal places POC
micro-gC/l
Three digits and one decimal places PON
micro-gN/l
Three digits and one decimal places
(4) Note
The analitical results of POC/PON were indicated all figure by a reason of nothing the evaluation method, and also, the quality flag were not indicated.
The temperature and salinity data of Middle Layer(300 to 3000m) and Deep Layer(3000m to bottom) were not listed on the data sheet, because this sampling were operated with HYDROGRAPHIC cast. The sampling on the Shallow Layer(0 to 300m) for POC/PON were carried out using a single cast separating from the HYDROGRAPHIC cast while temperature and salinity measurements were carried out to identify the water qualities and listed.@
Table 1 Cruise File name Observation layer NH92-2 N922SP.xls Shallow N922MP.xls Middle NH93-1 N931SP.xls Shallow N931MP.xls Middle NH93-2 N932SP.xls Shallow N932MP.xls Middle N932DP.xls Deep NH94-1 N941SP.xls Shallow N941MP.xls Middle N941DP.xls Deep NH94-2 N942SP.xls Shallow N942MP.xls Middle N942DP.xls Deep NH95-1 N951SP.xls Shallow N951MP.xls Middle* NH95-2 N952SP.xls Shallow
