1. Cruise Narrative

1.1 Highlights

Expedition Designation(EXPOCODE): 49RY9306

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 Rabaul, Papua New Guinea
          Leg 2: Rabaul, Papua New Guinea to Cebu, Republic of the
                    Philippines
          Leg 3: Cebu, Republic of the Philippines to Tokyo, Japan

Cruise Dates:
          Leg 1: June 9, 1993 to June 26, 1993
          Leg 2: June 29, 1993 to July 12, 1993
          Leg 3: July 17, 1993 to July 31, 1993

1.2 Cruise Summary

Cruise Track
          The cruise track and station locations are shown in Figure
1. Observations of PR4 were carried out as part of the R/V Ryofu
Maru cruise RY9306 Leg 1, and those of PR2 were Leg 2 and Leg 3.

Number of Stations
          A total of 35 CTD/rosette stations for PR4 and 32 stations
for PR2 was occupied using a General Oceanics 12 bottle rosette
equipped with 12 2.5-liter Niskin water sample bottles, and a
Falmous Scientific Inc. Integrated 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 at every 5 degrees in latitude. On other
stations, samples were taken at shallower depths than 1250m.
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
          I. Terashima          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 Falmous Scientific Inc. Integrated CTD. A
Compaq DeskPro 486/33  with 16 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). All of the data was
primary recorded in RAM disk, and after the observation, data was
processed following Millard and Yang(1992).

          The temperature and pressure sensor were calibrated at the
calibration facility of FSI before the shipping and the
calibration table in the facility is updated.

          The conductivity sensor was calibrated at sea using data
from the measurements of salinity collected at 9 stations on PR4
and 9 stations on PR2. The salinometer is Guildline Portasal model
8410 for the measurements of salinity of the water samples. We used
the batch P118 of IAPSO as standard sea water to calibrate the
salinometer. The results are shown in Table 3. The calibration
constant is determined assuming that the bias zero.


                                          Bias               Slope

          RY8462-8471                      0.0             1.00010
          RY8472-8476                      0.0             1.00027
          RY8477                           0.0             1.00018
          RY8478-8496                      0.0             1.00027
          RY8497-8508                      0.0             1.00029
          RY8511-8531                      0.0             1.00036


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 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 final storage data files do not have the
field of the number of samples and we processed CTD files from
those.

3. References

Japan Meteorological Agency, 1970: Kaiyo Kansoku Shishin (Manual
          on Oceanographic Observation). (in Japanese)
Millard, R and Keqi Yang, 1992: CTD Calibration and Processing
          Methods used by Woods Hole Oceanographic Institution.
          (Draft)
