                  R/V Chofu Maru Cruise NC9310


1 Cruise Narrative


1.1 Highlights

Expedition Designation   Chofu Maru Cruise NC9310

Chief Scientist          Yoshisuke Tomiyama, NMO

Ship                     R/V Chofu Maru

Port of Call             Ishigaki
                         
Cruise Dates             Leg 2: October 29 to November  2, 1993
                         Leg 3: November 6 to November 11, 1993


1.2  Cruise Summary

     Observations of PR19 were carried out as a part of the R/V
Chofu Maru Cruise NC9310 Leg 2 and Leg 3. The ship sailed from Naha
at 0500 UTC on 29 October 1993.  By 2202 UTC on 29 October, the
ship was at the first station of a section PR19. When the
observation at NS-6 on a section PR19 finished at 2246 UTC on 30
October, we interrupted the observation of PR19 by the Typhoon 9323
was approaching, and the ship sailed for Ishigaki. The ship
returned to the station NS-5 at 1444 UTC on 6 November and
restarted the observation. The observations of PR19 finished at
1135 UTC on 8 November.

       The cruise track and station locations are shown in Figure
1. Water sampling on the cruise included measurements of salinity
both by CTD and by water bottle samples, CTD temperature, bottle
sample oxygen determination, and nutrients (nitrates, nitrites, and
phosphates).  


1.3 Principal Investigators for All Measurements

     The principal investigators for all the parameters measured on
the cruise are listed in Table 1.

Table 1. Principal Investigators for All Measurements

       Name           Responsibility      Affiliation

      T. Tomiyama      CTD,S                 NMO
      K. Kimura        O2,Nutrients          NMO

1.4 List of Cruise Participants

     The cruise participants are listed in Table 2.

Table 2. Cruise Participants

       Name           Responsibility      Affiliation

      NC9310 Leg 2    Naha to Ishigaki    29 Oct. to  2 Nov.
      NC9310 Leg 3    Ishigaki to Naha     6 Nov. to 11 Nov.

      Y. Tomiyama      Chief Scientist,       NMO
                       CTD,S,O2
      M. Suzuki        CTD Hardware           NMO
      N. Nagai         O2                     NMO
      H. Daimon        CTD software           NMO
      T. Shimizu       O2,Nutrients           NMO
      J. Jifuku        O2,Nutrients           NMO
      T. Chagihira     CTD Software           NMO
      S. Shiraishi     S                      NMO
      S. Wakaki        Maritime Meteorology   NMO
      T. Tashiro       Maritime Meteorology   NMO
                                                 
                                                  Y.T


2. CTD

     The NBIS Mark III B CTD (6500 dbar sensor without oxygen
sensor) mounted on the 12 x 1.7 Liter General Oceanics rosette
multisampler frame was used for all of the vertical CTD work. At
some stations of which depth are deeper than 1,000 meters, the
PREUSSAG acoustic pinger was mounted on 10 meters above the frame.
At other shallower stations, the package was lowered to the depth
of 95 percents of the bottom depth without the acoustic pinger.

     The performance of the CTD and multisampler was good
throughout the cruise.

     The details of the data collection and data processing methods
are described in "CTD Full Sampling and Data Processing Method Used
at Nagasaki Marine Observatory". These methods were based on
Millard and Yang ( 1992 ). 

     The results of the laboratory calibration for the temperature
and pressure are shown in Table 3. 






Table 3. CTD calibration constants at laboratory

          Temperature; linear fit

             Time             Bias        Slope

Pre -Cruise  6 Oct. 1993      0.0063225   1.0000818


          Pressure increasing (0-6500 dbar range); linear fit

             Time             Bias        Slope

Pre -Cruise  6 Oct. 1993      0.9742484   1.0000864


          Pressure decreasing (0-6500 dbar range); linear fit

             Time             Bias        Slope

Pre -Cruise  6 Oct. 1993     -3.8425722   1.0009821

     The conductivity scaling factors are derived from a linear fit
of CTD data to water sample data and were used for the final data
load. These factor are given in Table 4. The salinity determination
of the water samples was with the Guildline AUTOSAL 8400A. Standard
Seawater batch of P121 was used to standardize the AUTOSAL. The
precision of the salinity determination of the water samples was
0.0004 PSS on leg2 and 0.0004 PSS on leg3 derived from the standard
deviation of the twenty-five and thirty-six water samples collected
from the same bottle respectively.


Table 4. The conductivity scaling factor; linear fit

Station No.         Bias           Slope
NS-8 - NS-6       -0.004339       1.000458
NS-5 - IS-13       0.001325       1.000328

     A temperature time lag was decided the CTD time constant
decision program, time lag was 0.192 seconds. The ITS-90 scale was
used for the temperature and potential temperature.

                                                  Y.T 


3. Oxygen measurements

     The determination of dissolved oxygen was done by the modified
version of the Winkler method described in "Kaiyou kansoku shishin
(Manual of Oceanographic Observation)" published by the
Oceanographical Society of Japan (1970). The reagent blank was not
subtracted. The results of the estimation of precision are shown in
Table 5. No estimation of accuracy has been made.


Table 5. The precision of oxygen analyses by three analysts

          Sample Number  Average   One sigma      precision
                         umol/l    umol/l         %

Analyst A      10        203.1     1.16           0.57
Analyst B      10        203.9     0.27           0.13
Analyst C      10        204.0     0.86           0.42
Analyst D      10        203.9     0.40           0.20

                                                       K.K


4. Nutrient analyses

     The nutrients analyses were done by the Technicon Auto
Analyzer II described in "Kaiyou kansoku shishin (Manual of
Oceanographic Observation)" published by the Oceanographical
Society of Japan (1970).

     Sampling for nutrients followed that for dissolved oxygen on
average 10-20 minutes after the casts were on deck. Samples were
drawn into 10 cm3 glass, narrow mouth, screw-capped bottles. Then
they were immediately introduced on the sampler tray of the
Technicon Auto Analyzer II for the analysis and generally the
analyses were begun within one hour after the casts were on deck.
If the delays were anticipated to be more than one hour, the
samples were refrigerated. Samples were refrigerated and stored up
to one hour on stations NS-7,NS-2,NS-1 and all of IS-line.

     The precision of the onboard Nitrate and Nitrite analyses
estimated from the standard deviation of the five samples from the
same working standard solution on each analysis are shown in Table
6. The precision of the onboard Phosphate analysis estimated from
the standard deviation of the four samples from the same working
standard solutions are also shown in Table 5. The concentrations of
the working standard of nitrate, nitrite and phosphate were 40
umol/l, 2 umol/l and 3 umol/l, respectively. No estimation of
accuracy have been made.


Table 6. The median and the range ( in the parentheses ) of the
precision of the onboard nutrients analyses.

       Nitrate          Nitrite          Phosphate     unit:%

        0.187            0.129            0.381
    (0.051-1.924)    (0.035-2.146)    (0.063-3.797)       

     The concentrations in umol/kg of oxygen, nitrate, nitrite and
phosphate were converted from the concentrations in umol/l using
the density calculated from the room temperature and salinity of
the water samples. The laboratory temperature for each station are
given in Table 7


Table 7. Laboratory temperature for each station.***********

Station   Temp.     Station   Temp.     Station   Temp.
NS-8      31.6      NS-7      30.4      NS-6      31.9
NS-5      30.4      NS-4      30.7      NS-3      30.8
NS-2      31.7      NS-1      31.1
IS-1      30.6      IS-2      30.7      IS-3      30.9
IS-4      31.1      IS-5      31.0      IS-6      30.8
IS-6a     29.9      IS-6b     29.8      IS-7      29.8
IS-7'     31.5      IS-8      31.5      IS-9      31.6
IS-10     31.6      IS-11     31.1      IS-12     31.1
IS-13     31.1

                                                       K.K


5. Notes for the --.SUM,--.SEA and --.CTD files

     The first 2 characters of the file name of --.SUM, --.SEA and
--.CTD files  are NC for R/V Chofu Maru of Nagasaki Marine
Observatory. These characters are followed by the last two digits
of year, the month and character R (R for PR18) or character S (S
for PR19) for the --.SUM and --.SEA files. In addition, the leg of
the cruise is appended in the file name of --.SEA files. For the --
.CTD files The characters NC are followed by the unique station
number and the cast number given in the Comments.

     The file names of the --.SUM and --.SEA for this cruise are as
follows;

     NC9310S.SUM, 
     NC9310S2.SEA 


5.1 --.SUM

     Since some of the water depth of the cast were not recorded,
we leave the column of them blank. 

     Since the surface water samplings were by a stainless steel 
water bucket, "Number of bottles" includes this bucket sampling.  

     The unique station numbers given by the Japan Meteorological
Agency with the cast numbers, which are used as the --.CTD files
name, are given in the "Comments".
5.2 --.SEA

     We leave "the sample number (SAMPNO)" blank because the sample
numbers are different among the salinity, oxygen and nutrients on
our assignments.  

     Since the surface water samplings were by a stainless steel 
water bucket, we leave the column of  "The Bottle Number (BTLNBR)"
at the surface layer blank. 

     All water sample quality flags for the oxygen during this
cruise were "3" because the precision did not exceed the WOCE
standard of 0.1% and no estimation of accuracy has been made.


5.3 --.CTD

     The files name were given in the Comments of --.SUM files.

                                                       Y.T


6.GPS
     Standard deviation of the position data by the GPS system are
shown in Table 8. The position data were good throughout the
cruise.


Table 8. Standard deviation of the position data

Date     Port           Standard deviation
                        Latitude        Longitude
Nov. 5   Ishigaki       43.6m           20.3m
Nov.14   Naha           24.3m           20.2m

                                                       Y.T


7. References

Aoyama,M, S.Saito, T.Kobuchi and S.Shiraishi, 1993: CTD full
Sampling and Data Processing Method Used at Nagasaki Marine
Observatory. (Draft)

Millard,R and Keqi Yang, 1992: CTD Calibration and Processing
Methods used by Woods Hole Oceanographic Institution. (Draft)

Oceanographical Society of Japan, 1970: Kaiyou kansoku shishin
(Manual of Oceanographic Observation). Ed. by the Japan
Meteorological Agency. (in Japanese)
