Preliminary Report
may 15, 1995

A.	Cruise Narrative
A.1.	Highlights
A.1.a	WOCE designation:	PR16
A.1.b	EXPOCODE:		31DSEP390/2
A.1.c	Chief Scientist: Ben Moore
                 	 National Oceanic and Atmospheric Administration  
                 	 Pacific Marine Environmental Laboratory

A.1.d	Ship Name: NOAA R/V DISCOVERER R-102.

A.1.e	Ports of Call
  
A.1.f	Cruise Dates: November 26 - December 6, 1990

A.2	Cruise Summary

A.2.a	Geographic boundaries

Location:  Along 110W from 5S to 16N and along the equator from 125W to 110W.

A.2.b	Total number of stations Occupied

A.2.c	Floats and drifters deployed

A.2.d	Moorings deployed or recovered

A.3 	List of Principal Investigators

Principal Investigator: Stanley P. Hayes
                        National Oceanic and Atmospheric Administration  
                        Pacific Marine Environmental Laboratory

A.4	Scientific Programme and Methods

A meridional hydrographic section along 110W from 5S to 16N was made
on leg 2 of the fall EPOCS (Equatorial Pacific Ocean Climate Studies)
cruise in the Eastern Tropical Pacific.  Also during this leg, a zonal
hydrographic section was made along the equator from 125W to 110W.
Operations took place aboard the NOAA research vessel DISCOVERER R-102.  

Underway operations included continuous determination of sea surface
temperature (SST) and meteorological parameters, Acoustic Doppler Current
Profiler (ADCP) measurements, intermittent XBT casts and water samples for
bucket temperatures, sea bird and marine mammal observations during
daylight hours, and sea surface gravity and bathymetry.  Although the
primary objective of the cruise was the recovery and deployment of moored
temperature buoys, there were also drifting buoy deployments, an inverted
echo sounder (IES) recovery, two current meter mooring recovery and
deployments, and 31 "small volume" CTD/rosette casts with on-board seawater
analyses of salinity. (Analyses of nutrients, productivity, and nitrogen
uptake were cancelled at the last minute.)  

A Neil Brown MKIII CTD, serial number 1111, was used throughout leg2.
There was no oxygen sensor added to this fish, and the fast response
temperature sensor had been disabled.  Because of time gained during
mooring operations, extra CTD casts were added along 110W for a total of 27
casts along this section beginning at 5S, spaced every one degree of
latitude with half-degree spacing equatorward of 2 degrees to 16N.  Three
casts were made along the equator every 5 degrees of longitude from 125W to
115W, and a single test cast was made at 7N, 140W.  Out of a total of 31
casts, 6 were deep casts, 23 were taken to a depth of 1000 meters, and 2
were taken to a depth of 500 meters. Because the ship's pingers caused
sever spiking in the pressure channel near the end of leg 1, no pinger was
mounted during leg 2 and the packaged was kept 200 meters off the bottom
during deep casts. (The bottom depth was provided by the ship's seabeam.)  

The NOAA-sponsored EPOCS research program is an ongoing research
effort that began in 1979 and is designed to further understanding of the
role of the tropical ocean in modifying the world's climate.   EPOCS
contributes to the WOCE Hydrographic Program's efforts to describe and
understand the global ocean circulation, its decadal changes, and its
influence on climate.  

A.5	Major Problems and Goals not achieved

A.6	Other Incidents of Note

A.7	List of Cruise Participants

		Table 1:  List of Cruise Participants
--------------------------------------------------------------------------
Name			Institution	Responsiblity
---------------------------------------------------------------------------
Ben Moore               PMEL    temperature buoy recovery and deployment
(Chief Scientist)
Kevin Kinsey            PMEL    temperature buoy recovery and deployment
Julia Nichols           PMEL    temperature buoy recovery and deployment
Doug Fenton             PMEL    Current Meter recovery and deployment
Kristy McTaggart        PMEL    CTD acquisition and on-board processing
Larry Speak             PRBO    Bird and marine mammal observations
Steve Howell            PRBO    Bird and marine mammal observations
Nina Karnovsky          PRBO    Bird and marine mammal observations
Sophie Webb             PRBO    Bird and marine mammal observations

The principal investigator responsible for sample and CTD analysis
and interpretation is Dr. Stanley P. Hayes of the National Oceanic and
Atmospheric Administration Pacific Marine Environmental Laboratory.  

B.	Underway Measurements

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

C.	Hydrographic Measurements

VERTICAL SECTIONS
   
Note that stations north of 10N are not on the 110W line but along the cruise
track from 10N, 110W to 16N, 113W.  The bottle depth distribution for the
small volume samples were approximately as follows with an extra bottle (a
PMEL prototype) tripped at one of the deeper stops.  

       DEEP CASTS                1000m CASTS

       bottom-200                   1000
       4000                          900
       3750                          800
       3500                          700
       3000                          500
       2000                          250
       1000                          100
       500                           sfc
       100
       sfc*

                                                                               
ACQUISITION:                                                               
                                                                               
     A Neil Brown Mark III CTD, serial number 1111, was used throughout leg    
     two of the fall 1990 EPOCS cruise measuring pressure, temperature, and    
     conductivity (no oxygen sensor).  Because of time gained during mooring   
     operations, extra CTD casts were added to the project at every degree of  
     latitude along 110W from 5N to 16N for a total of 27 casts along this     
     section beginning at 5S.  Three additional casts were made along the      
     equator every 5 degrees of longitude from 125W to 115W, and a single      
     test/calibration cast was made at 7N, 140W.  Out of a total of 31 casts,  
     6 were deep casts, 23 were taken to a depth of 1000 meters, and 2 were    
     taken to a depth of 500 meters.  Because the ship's pingers were shown    
     in the real-time analog plots of temperature and conductivity verses      
     pressure to interfere with the CTD data stream causing severe spiking     
     in the pressure channel, there was no pinger mounted during the deep      
     casts and the package was kept 200 meters off the bottom.  (The bottom    
     depth was provided by the ship's Seabeam.)                                
                                                                               
     The CTD data stream was passed through a Neil Brown Mark III deck unit.   
     An analog signal was displayed on an XYY' plotter to monitor the quality  
     of the transmission in real-time; an audio signal was recorded onto tape  
     as a backup; and digitized data was sent to a Zenith personal computer    
     equipped with EG&G CTD acquisition software where it was calibrated and   
     displayed in listing and graphical forms in real-time, as well as         
     documented and stored in raw form onto the hard disk.  All equipment      
     performed well and there were no signs of misfires associated with the    
     General Oceanics rosette sampling system.  Shipboard processing was done  
     using programs generated at PMEL on a shipboard microVAX system.          
     Preliminary analysis of cast profiles showed the data to be of good       
     quality.                                                                  
                                                                               
     Also, a prototype water sampling bottle produced at PMEL was tested on    
     each cast.  This bottle was tripped at the same depth as a ship's Niskin  
     bottle and their salinities compared.  These numbers showed the prototype 
     to be of equal quality.                                                   
                                                                               
                                                                               
     SALINITIES:                                                               
                                                                               
     Salinity was the only analysis performed on the water samples collected.  
     Guildline Autosal 56.118, last calibrated at NRCC 1/9/90, was used to run 
     salinities for all casts by CST Murray.  IAPSO standard seawater used     
     was lot #P110.  Operating temperature was 24C.  Drift corrections were    
     applied by survey before being transcribed to the CTD cast logs.          
                                                                               
     A second sample from one of the deeper bottles from each cast was run on  
     a subsequent day to check the Autosal and it's drift.  These numbers      
     showed the salinometer to have worked well throughout the cruise.  Also,  
     reversing thermometer temperature and thermometric depths were reasonable.
                                                                               
                                                                               
     CONDUCTIVITY CALIBRATIONS:                                                
                                                                               
     CALIB.DAT precruise calibrations for CTD 1111:                            
                                                                               
     1111    6  380                                                            
     -19.3940   .9960320  0.190816E-5  -0.2018487E-09   P DN  S/N 1111  JUL 90 
     -21.3632   .9937291  0.302192E-5  -0.3140824E-09   P UP  S/N 1111  JUL 90 
       0.0498  1.0007090  0.000000E-6   0.0000000E-10   T 68  S/N 1111  JUL 90 
       0.0010  0.9999194  0.000000E-6   0.0000000E-10   C     S/N 1111  JUL 90 
                                                                              
     LINCALW was run on the whole and a cast break was seen between casts 10 
     and 11.  Linear fit coefficients used in EPCTDW and CALMSTRW for casts 
     1-10 were                                                                 
                                                                              
		A(0) =  -1.6119338E-03                                         
		A(1) =   0.9999725                                             
 		standard deviation =  1.6040863E-03                            
                                                                               
     Coefficients for casts 11-31 were                                        
                                                                              
		A(0) =   1.4693985E-03                                         
		A(1) =   0.9998032                                            
		standard deviation =  1.6934872E-03                            
                                                                               
     DEEPCTD plots with the above calibrations applied showed poor correlation 
     between deep CTD traces and deep bottle salinities.  A linear fit was     
     applied to (a) only deep EP390 CTD and bottle conductivity pairs for     
     group 1 and 2, (b) deep EP390 CTD and mean historical bottle conductivity

 
     pairs for group 1 and 2, and (c) deep EP390 CTD and mean historical bottle
     conductivity for each deep cast.  As a whole, EP390 CTD and bottle data   
     looked a bit fresher than historical data in the deep water.  Calibrating 
     the CTD to just the deep bottles, or to historical bottle data didn't    
     improve the discrency consistently for all deep casts.  So the data      
     was submitted to WHPO with the original fit coefficients listed above.   
     Further investigation may take place at a later date.                    
                                                                              
     CONDUCTIVITY CALIBRATION PROGRAMS & PPLUS COMMAND FILES:                 
                                                                              
     CALDSKW - creates .CAL uncalibrated data file on SCS system              
     CALMSTRW - inputs .CAL uncalibrated data file                            
              - outputs .CLB calibrated data file (from .COM), and            
                .SEA calibrated WOCE data file (edit quality bytes)           
     LINCALW - inputs .CAL uncalibrated data file (may be broken into         
               groups), applies a linear fit to the data and throws out       
               any points greater than 2.8 times the standard deviation,      
               iterates through the program until no points are thrown out
	       outputs .COEF file containing linear fit coefficients and      
	       .LOG file of fit iterations                                    
     CALMCONW.PPC - reads .CLB calibrated bottle data file and makes five     
                    separate scatter plots: P, T, C, S, and cast number vs.   
                    delta-C (CTD-bottle).  These are examined for cast       
                    breaks and drifts in the CTD.                            
     CALMDEEPW.PPC - reads .CLB calibrated bottle data file and makes two    
                     separate scatter plots: CTD salinity and bottle salinity 
                     vs. potential temperature from theta=0.6 to 2.2 C.      
     DEEPCTD.PPC - reads .CTD EPIC pointer file and .BOT EPIC pointer file   
                   of deep casts only and overplots the bottle salinity     
	           data and CTD salintiy trace from theta=.8 to 2.4 C for     
	           each deep cast.                                            
                                                                              
                                                                              
     PROCESSING:                                       
                                                                 
Processing with precruise calibrations were done at sea on a microVAX II   
computer system.  During the last week of the cruise, parity errors began  
to increase and processing was halted.  Data files were restored in the    
lab from TK50 tape.                                                        
                                                                      
DPDNZ - inputs EG&G .EDT raw data file                                     
      - outputs .DPZ binary file including computed fall rates and         
             .RECZ ASCII file to choose downcast record range from         
DLAGZ - inputs .DPZ binary file, applies precruise calibrations from       
        CALIB.DAT, edits data for window outliers (according to            
        WINDOW.DAT) and first differencing outliers, fills gaps by         
        linear interpolation, lags conductivity, edits data exceeding      
        fall rate criteria (according to .INP created by DLAGAVZ.COM;      
        default minimum fall rate acceptable is .8 db/60 scans (25         
        meters per minute) and pressure interval of 1.5 db; doesn't        
        fill these gaps), computes 1-meter averages, and applies cell      
        dependence to final conductivity values                            
        - outputs CTDERR.DAT file of outlier flags, interpolated values,     
        and fall rate criteria failures, and an ASCII .CTD data file       
        including computed salinity                                        
EPCTDW - inputs .CTD calibrated P, T, OXC, OXT, and raw conductivity;      
       applies any additional P and T cals (in EPCTDW_SHIP.COM),         
       corrects raw C for cell factor, and applies C cals from           
              
EPCTDW_SHIP.COM; computes salinity; deals with oxygen if          
         there was a sensor; eliminates 1-point spikes according to        
         the gradients hardwired into the source code; omits any           
         values for manual despiking; fills by linear interpolation        
         for a value to exist every whole meter; recomputes C from         
         S; and calculates other EPIC variables.                           
         - outputs final .CTD data file in EPIC format, and a .LOG           
         file listing editted and filled data points                       
     
EPICBOMSTRW - inputs .CLB calibrated bottle data file and                  
            .CTD EPIC data files (for header information)                
            - outputs .BOT bottle data files in EPIC format                
TSPLTEP.PPC - reads .CTD EPIC pointer file and .BOT EPIC pointer file      
             and overplots full water column bottle salinity and CTD      
             trace as well as sigma-t lines (from SIGMAT.DAT). Use        
	     TSPLTB.PPC to include oxygen data.                
TEXTNOX - inputs .CTD EPIC pointer file and constructs PPLUS subcommand    
          files                                                            
        - outputs TXT*.PPC files containing %label commands for table     
          listings for each cast                                             
3PLTNOX.PPC - reads TXT*.PPC subcommand files and .CTD EPIC pointer        
       	    file and overplots vertical profiles of temperature,         
            salinity, and sigma-t vs. pressure to 1000 db on left-
            hand side of page; and lists data in table form on               
            right-hand side of page.  Use 4PLT1DB.PPC to include  
            oxygen data.                                     
                                                                             
DLAGZ was run with default minimum fall rate and pressure interval         
criteria.  EPCTDW was run without gradient despiking except in the case    
of cast 4 where the original raw data was lost due to an operator error    
and the 1000 meter cast had to be replayed from audio tape on the Akai     
reel-to-reel tape recorder.  The tapes had been reused repeatedly from     
cruise to cruise and some oxidation had occurred making the replay very    
noisy.  Also, unfortunately, the recording levels had dropped during cast  
4 and was not noticed by the operator.  Only the first 500 meters of the   
cast was recoverable.                                                      
                                                                               
TSPLTEP and DEEPCTD plots were looked at for any spiking that needed to    
be removed manually (i.e. using the NOMIT subroutine in EPCTDW).  Spikes   
were removed from casts nearly every cast except for casts 1, 10, 13, 15,  
17, 19, 30, and 31; and data was replaced by linear interpolation.         
                                                                               
Final CTD and bottle files were moved to DISK$HAYES and included in the    
RIM data management tables on November 7, 1991.                            
                                                                           
                                                                           
WOCE SUBMISSION:                                                           
                                                                           
Because EP390 collected data along 110W, WOCE repeat line PR16, a cruise   
plan was submitted prior to the cruise and a cruise report was submitted   
afterwards on January 30, 1991.  In July 1991, a revised WHP manual of     
hydrographic data reporting requirements was distributed.  CTD data files  
and bottle data .SEA file were finalized for submission according to       
these new specifications on November 11, 1991.  A new .SUM file was not    
submitted.                                                                 
                                                                           
In the .SEA file, BTLNBR, CTDSAL, and SALNTY were assigned quality flags   
as follows.                                                                
                                                                           
BTLNBR:  Not all of the bottles are accounted for here.  If a sample was   
not drawn from a bottle, it was ommitted from this file instead of given   
a quality byte value of 9.  The definitions for byte values used were 2    
'no problems noted', 3 'leaking' (as noted on the sampling sheets and      
CTD cast logs), and 4 'did not trip correctly' (given if the nominal       
depth at which the bottle was supposed to have been tripped differed       
from the actual depth).                                                    
                                                                           
CTDSAL:  All CTD salinity values in this file were considered acceptable.  
                                                                          
SALNTY:  An in-house criteria was set up to distinguish between acceptable,
questionable, and bad quality byte values for bottle salinity measurements.
For the highly variable upper water column (0-1000 db), if the difference  
between the CTD salinity and bottle salinity was greater than .04 psu,     
SALNTY was assigned a byte value of 4 'bad'; if the difference was between 
.01 and .04 psu, SALNTY was assigned a byte value of 3 'questionable';     
and if the difference was less than .01, it was considered an acceptable   
bottle salinity.  For the more stable deep water (potential temperature    
less than 2.4 C), SALNTY was considered bad if the difference in           
salinities was greater than .008 psu, questionable if delta-S was between  
.003 and .008 psu, and acceptable if less than .003 psu.  For mid-column   
water, the assignment of byte values was subjective.         


D.	Acknowledgments
E.	References

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 ep390.sum, 
ep390.hyd, ep390.csl and *.wct files.  The ep390.sum file contains a summary of
the location, time, type of parameters sampled, and other pertient
information regarding each hydrographic station.  The ep390.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 ep390.wct.zip. The ep390.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 ep390.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 Evaulations
