preliminary data report
may 19, 1995
A.	Cruise Narrative
A.1	Highlights
A.1.a	WOCE designation	PR18
A.1.b	EXPOCODE		49TU9101/2
A.1.c	Chief Scientist 	Harruo Miyagi, NMO
A.1.d	Ship		        R/V Chofu Maru
A.1.e	Port of Call		None
A.1.f	Cruise Dates		January 24 to January 31, 1991

A.2	Cruise Summary
A.2.a	geographic boundaries
A.2.b	total number of stations occupied
A.2.c	Floats and drifters deployed
A.2.d	Moorings deployed

A.3	List of Principal Investigators
 
Table 1. Principal Investigators for All Measurements

       Name           Responsibility      Affiliation
      -----------------------------------------------
      I. Kaneko        CTD                   NMO
      M. Aoyama        S,O2,Nutrients        NMO
      T. Matsubara     Maritime Meteorology  NMO
      -----------------------------------------------

A.4	Scientific Programme and Methods    

Observations of PR18 were carried out as a part of the R/V
Chofu Maru Cruise NC9101.  The ship sailed from Hakata at
0600 UTC on 24 January 1991.  By 0100 UTC on 27 January the ship
was at the first station of a section PR18. At 1654 UTC on 27
January just finished the observation at PN-5, we interrupted the
observation of PR18 and took 10 hours trip to the ocean data buoy
near the PR18 line. The location of the ocean data buoy is 28
10'N, 126 20'E and the depth at the buoy is 133 meters depth. The
purpose of this  was the routine maintenance and confirmation of
the buoy. The ship returned to the station PN-5 on section PR-18
at 0240 UTC on 28 January and started the observation again. The
CTD and multisampler were good throughout the cruise.  

Course was set for Naha and rostered watches finished at
1500 UTC on 30 January 1991.

A.5	Major Problems and Goals not achieved
A.6	Other Incidents of Note
A.7	List of Cruise Participants

		Table 2. Cruise Participants
      ---------------------------------------------------	
       Name           Responsibility      Affiliation
      H. Miyagi        Chief Scientist        NMO
      M. Aoyama        S,O2,Nutrients         NMO
      N. Ishikawa      Watch Stander          NMO
      T. Nakano        CTD Hardware,          NMO    
                       CTD Software          
      H. Kamiya        Watch Stander          NMO
      T. Shimizu       O2,Nutrients           NMO
      T. Ishihara      Watch stander          NMO
      T. Tsutsumida    Watch stander          NMO
      T. Matsubara     Maritime Meteorology   NMO
     ---------------------------------------------------      

                                                    
B.	Underway Measurements

B.1	navigation and bathymetry
B.2	Acoustic Doppler Current Profiler (ADCP)
B.3	Thermosalinograph and underway dissolved oxygen, fluorometer, etc.
B.4	XBT and XCTD
B.5	Meteorological observations
B.6	Atmospheric chemistry

C.	Hydrographic Measurements

The Neil Brown Mark III B CTD (1600 dbar sensor without
oxygen sensor) mounted in the 12 x 1.7 Liter General Oceanics
rosette multisampler frame was used for all of the vertical CTD
work.

In general at the CTD stations of which depth are shallower
than 100 meters and than 4000 meters, the package was lowered to
within 5 meters of the bottom and lowered to the depth of 95
percents of the bottom depth, respectively, because unable to use
the acoustic pinger on DSF-6000 fathometer. 

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

A Hewlett Packard HP9000-320 with a 2 MByte of memory was
used as a primary data collection device and all CTD data was
backed up onto the audio tape. The original sampling rate is
31.25 samples per second, however, our software can get around 20
samples per second and compress it one sixth  of the collected
data due to the limitation of the memory. All of the CTD data of
our observatory was loaded on the basis of the compressed data
described above. 

The results of the laboratory calibration for the tempera-
ture and pressure are shown in Table 3, however, these were not
used because the calibration methods for temperature and pressure
are not decided. 

Table 3. CTD calibration constants at laboratory
-----------------------------------------------------------------
          Temperature; linear fit
               Time             Bias        Slope

Pre -Cruise   20 Dec. 1989      0.0047014   0.9998922
Post-Cruise   12 Mar. 1991      0.0022534   0.9999701
 
          Pressure increasing (0-1600 dbar range); linear fit

               Time             Bias        Slope

Pre -Cruise   20 Dec. 1989      0.2653      0.999091
Post-Cruise   12 Mar. 1991     -0.0525      0.999349
-----------------------------------------------------------------


The conductivity scaling factor given in Table 4 is derived
from not a linear fit but a ratio of CTD data to water sample
data and were used for the final data load. The salinity determi-
nation of the water samples was with the Guildline AUTOSAL 8400A.
Standard Seawarter batch of P112 was used to standardize the
AUTOSAL. The precision of the salinity determination of the water
sample with the Guildline AUTOSAL 8400A was 0.0007 PSS derived
from the standard deviation of the thirteen water samples col-
lected from the same bottle.


Table 4. The conductivity scaling factor
------------------------------------------
Station No.         Bias      Slope
PN-1 - PN-9           -       0.99984
------------------------------------------ 

Oxygen measurements
               
The determination of dissolved oxygen was done by the modi-
fied 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 precision was generally better than 1 umol/l
at the concentration of surface level. No estimation of accuracy
has been made.

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-6,PN-4',PN-3',PN-3 and
PN-2.

No estimations of accuracy and precision have been made.


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 salin-
ity of the water samples. The laboratory temperature for each
station are given in Table 6.

Table 6. Laboratory temperature for each station.
--------------------------------------------------------
Station   Temp.     Station   Temp.     Station   Temp.
--------------------------------------------------------
PN-9      24.       PN-8      24.       PN-7      24.
PN-6      29.       PN-5      29.       PN-4      25.
PN-4      25.       PN-3'     26.       PN-3      25.
PN-2      25.       PN-1      27.                    
--------------------------------------------------------
                                                      

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;

     NC9101R.SUM, 
     NC9101R2.SEA 


--.SUM

Since some of the time at the bottom (BO) and completion
(EN) of the cast, the positions at the beginning (BE), bottom
(BO) and the completion (EN) of the cast and the water depth of
station 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".

--.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.

All water sample quality flags for the nutrients during this
cruise were "3" because the no estimation of accuracy and preci-
sion has been made. 

 --.CTD

The number of samples averaged at the pressure level, NUM-
BER, was the estimated value because original CTD data were lost
in the processing described in "Section 2. CTD".

   
D.	Acknowledgement
E.	References
                             
Oceanographical Society of Japan, 1970. Kaiyou kansoku shishin
(Manual of Oceanographic Observation). Ed. by the Japan Meteoro-
logical Agency. (in Japanese)


Unesco, 1983. International Oceanographic tables. Unesco Technical Papers in 
Marine Science, No. 44.

Unesco, 1991. Processing of Oceanographic Station Data, 1991. By JPOTS
editorial panel.

F.	WHPO Summary

Several data files are associated with this report.  They are the tu91012.sum, 
tu91012.hyd, tu91012.csl and *.wct files.  The tu91012.sum file contains a 
summary of the location, time, type of parameters sampled, and other pertient
information regarding each hydrographic station.  The tu91012.hyd file contains
the bottle data. The *.wct files are the ctd data for each station.  The *.wct 
files are zipped into one file called tu91012.wct.zip. The tu91012.csl file is 
a listing of ctd and calculated values at standard levels.

The following is a description of how the standard levels and
calculated values were derived for the tu91012.csl file:

Salinity, Temperature and Pressure:  These three values were smoothed from
the individual CTD files over the N uniformly increasing pressure levels.
using the following binomial filter-

	t(j) = 0.25ti(j-1) + 0.5ti(j) + 0.25ti(j+1) j=2....N-1

When a pressure level is represented in the *.csl file that is not
contained within the ctd values, the value was linearly interpolated
to the desired level after applying the binomial filtering.   

Sigma-theta(SIG-TH:KG/M3), Sigma-2 (SIG-2: KG/M3), and Sigma-4(SIG-4:
KG/M3): These values are calculated using the practical salinity scale
(PSS-78) and the international equation of state for seawater (EOS-80)
as described in the Unesco publication 44 at reference pressures of the
surface for SIG-TH; 2000 dbars for Sigma-2; and 4000 dbars for Sigma-4.

Gradient Potential Temperature (GRD-PT: C/DB 10-3) is calculated as the
least squares slope between two levels, where the standard level is the
center of the interval.  The interval being the smallest of the two
differences between the standard level and the two closest values.
The slope is first determined using CTD temperature and then the
adiabatic lapse rate is subtracted to obtain the gradient potential
temperature.  Equations and Fortran routines are described in Unesco
publication 44.

Gradient Salinity (GRD-S: 1/DB 10-3) is calculated as the least squares
slope between two levels, where the standard level is the center of the
standard level and the two closes values.  Equations and Fortran
routines are described in Unesco publication 44.

Potential Vorticity (POT-V: 1/ms 10-11) is calculated as the vertical
component ignoring contributions due to relative vorticity, i.e.
pv=fN2/g, where f is the coriolius parameter, N is the bouyancy
frequency (data expressed as radius/sec), and g is the local
acceleration of gravity. 

Bouyancy Frequency (B-V: cph) is calculated using the adiabatic
leveling method, Fofonoff (1985) and Millard, Owens and Fofonoff
(1990).  Equations and Fortran routines are described in Unesco
publication 44.

Potential Energy (PE: J/M2: 10-5) and Dynamic Height (DYN-HT: M) are
calculated by integrating from 0 to the level of interest.  Equations and 
Fortran routines are described in Unesco publication, Processing of 
Oceanographic station data.

Neutral Density (GAMMA-N: KG/M3) is calculated with the program GAMMA-N
(Jackett and McDougall) version 1.3 Nov. 94.  

G.	Data Quality Evaulation
