R/V Ryofu Maru Cruise RY9301

1. Cruise Narrative

1.1 Highlights

Expedition Designation(EXPOCODE): 49RY9301/1

Chief Scientist:  Michio Hirota,
                  Japan Meteorological Agency,
                  1-3-4, Otemachi, Chiyoda-ku,
                  Tokyo 100, Japan

Ship:             R/V Ryofu Maru

Ports of Call:
        Leg 1:    Tokyo, Japan to Marakal, Parau

Cruise Dates:
        Leg 1:    January 19, 1993 to February 6, 1993


1.2 Cruise Summary

Cruise Track
The cruise track and station locations are shown in
Figure 1. Observations of PR2 were carried out as part of the R/V
Ryofu Maru cruise RY9301 Leg 1.

Number of Stations
A total of 33 CTD/rosette stations for PR2 was occupied
using a General Oceanics 12 bottle rosette equipped with 12 2.5-
liter Niskin water sample bottles, and an NBIS MK III B CTD. No
additional sensors were used with the CTD system.

Sampling
The following water sample measurements were made:
salinity, oxygen, nitrate, nitrite and phosphate on all
stations. The depths sampled were: 10, 25, 50, 75, 100, 125,
150, 175, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000,
1250, 1500, 2000, 2500, 3000, 4000 in meters. Surface water
samples were collected by a bucket at every station.


1.3 List of Principal Investigators

The principal investigators responsible for each parameter
measured on the cruise are listed in Table 1. (All the
correspondence on these data should be addressed to the Director
of the Oceanographical Division, Marine Department, Japan
Meteorological Agency.)

          Name                  Responsibility           Affiliation
          ----------------------------------------------------------
          I. Kaneko             CTD, S                   JMA/MD
          K. Fushimi            O2, Nutrients            JMA/MD

          JMA/MD  Marine Department, Japan Meteorological Agency

Table 1. Principal Investigators for all measurements.



2. Measurement Techniques and Calibrations

2.1 CTD

The CTD is NBIS Mark III B. An HP9000 Series 300 model 330
(Hewlette Packard) with 4 MByte of memory was used as the primary
data collection device and all FSK signals of CTD data were backed
up using the digital audio tape (DAT). The original sampling rate
is 31.25 samples per second, however, our software gets around 20
samples per second and compress these into one tenth of collected
data.

The temperature and pressure sensor were calibrated at the
calibration facility of SEA Co., Ltd. before the cruise. The
results are shown in Table 2.


                    Temperature; linear fit

                     Time                Bias         Slope
Pre-Cruise     (8 October 1992)         +0.0128      0.999606


                    Pressure(increase); linear fit

                     Time                Bias         Slope
Pre-Cruise     (7 October 1992)         -2.3740      0.999878


Table 2. CTD Calibration contents at laboratory

The conductivity sensor was calibrated at sea using data
from the measurements of salinity collected at 8 stations. The
salinometer is AUTOLAB model 1601 for the measurements of salinity
of the water samples. The results are shown in Table 3. The
calibration constant is determined assuming that the bias zero.


                                          Bias              Slope
                                        ----------------------------
          RY8327-8359                      0.0             0.99998


Table 3. The conductivity scaling factor

The temperature in "-.SEA" and "-.CTD" files are described
with the international temperature scale of 1990 (ITS-90).


2.2 Oxygen Measurements

The determination of dissolved oxygen was done by the
modified version of the Winkler method described in "Kaiyo Kansoku
Shishin (Manual on Oceanographic Observation)" published by the
Japan Meteorological Agency(1970). The reagent blank was not
subtracted. No estimation of accuracy and precision has been done.

Because no temperature data when samples were taken from
bottles are recorded, it was assumed that the density of samples
is 1022.156 kg/m3 (which assume the temperature for 28 degree C and
salinity for 34.68) and use this value to convert from umol/l to
umol/kg.


2.3 Nutrients Analyses

The nutrients analyses were done by the Technicon Auto
Analyzer II described in "Kaiyo Kansoku Shishin (Manual on
Oceanographic Observation)" published by the Japan Meteorological
Agency(1970). No estimation of accuracy and precision has been
done.

Because no temperature data while analyses are recorded,
it was assumed that the density of samples is 1022.156 kg/m3 (which
assume the temperature for 28 degree C and salinity for 34.68) and
use this value to convert from umol/l to umol/kg.


2.4 Noted for the -.SUM, -.SEA and -.CTD files


2.4.1 -.SUM

Since the surface water samples were taken by a stainless
steel water bucket, "Number of bottle" includes this bucket
sampling.


2.4.2 -.SEA

Our following parameters have the less precision than the
required, we describe the last digit of data as blank to meet the
data format: CTD temperature, CTD salinity, salinity, oxygen and
nitrates.


2.4.4 -.CTD

CTD temperature and salinity data have the less precision
than the required, we describe the last digit of data as blank to
meet the data format.

The number of samples averaged at the pressure level was
not available because our software was not recording the number of
data during data processing.



3. References

Japan Meteorological Agency, 1970: Kaiyo Kansoku Shishin (Manual
   on Oceanographic Observation). (in Japanese)

