                  R/V Chofu Maru Cruise NC9304


1 Cruise Narrative


1.1 Highlights

Expedition Designation   Chofu Maru Cruise NC9304

Chief Scientist          Tomoaki Hinata, NMO

Ship                     R/V Chofu Maru

Port of Call             None

Cruise Dates             Leg 1: April 26 to May 6, 1993

  
1.2  Cruise Summary

     Observations of PR18 were carried out as a part of the R/V
Chofu Maru Cruise NC9304 Leg 1. The ship sailed from Nagasaki at
0600 UTC on 26 April 1993.  By 2151 UTC on 28 April, the ship was
at the first station of a section PR18. The cruise track and
station locations are shown in Figure 1.

     The observations of PR18 finished at 0827 UTC on 1 May. 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

      NC9304 Leg 1    Nagasaki to Naha       26 Apr. to 6 May

      T. Hinata        Chief Scientist,       NMO
                       CTD Hardware
      K. Kimura        O2,Nutrients           NMO
      E. Moriyama      CTD Hardware           NMO
      M. Suzuki        Watch Stander          NMO
      T. Shiga         S                      NMO
      H. Daimon        CTD Software           NMO
      J. Jifuku        O2,Nutrients           NMO
      T. Chagihira     CTD Software           NMO
      N. Nagai         Watch Stander          NMO
      H. Nakane        Maritime Meteorology   NMO

                                                     Y.T


2. CTD

     The NBIS Mark III B CTD (1600 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.

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

     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 26 Sep. 1992      0.0042191   0.9999142


          Pressure increasing (0-1600 dbar range); linear fit

             Time             Bias        Slope

Pre -Cruise 28 Sep. 1992     -0.1751734   0.9992790




          Pressure decreasing (0-1600 dbar range); linear fit

             Time             Bias        Slope

Pre -Cruise 28 Sep. 1992     -1.4067743   0.9999869


     The conductivity scaling factor given in Table 4 is derived
from a linear fit of CTD data to water sample data and were used
for the final data load. 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 0.0003 PSS
derived from the standard deviation of the twenty-six water samples
collected from the same bottle.


Table 4. The conductivity scaling factor; linear fit

Station No.         Bias           Slope
PN-1 - PN-9         0.010540       0.999769

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

                                                  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                                 1.28
Analyst B      10                                 1.01
Analyst C      10                                 0.62

                                                       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 PN-9,PN-8,PN-7,PN-5,PN-4',PN-4,PN-3'and
PN-3.  

     The precisions 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 6. 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:%

        0.271            0.302            0.426
    (0.071-1.302)    (0.036-1.877)    (0.052-2.411)       
    
     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.
PN-9      28.6      PN-8      31.5      PN-7      31.5
PN-6      31.6      PN-5      31.6      PN-4'     32.3
PN-4      30.1      PN-3'     29.5      PN-3      29.7
PN-2      31.6      PN-1      30.5                   

                                                       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;

     NC9304R.SUM, 
     NC9304R1.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
     For examine the accuracy of the position data of the GPS
systems, standard deviations were calculated in after cruise. The
position data were good throughout the cruise. The results are
shown in Table 8.


Table 8. Standard deviation of position data

Date      Port           Standard deviation
                         Latitude       Longitude
Apr. 26   Nagasaki       20.0m          28.0m

                                                       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)
