




                        1991 CRUISE REPORT FOR WOCE PR16:  
                     A REPEAT HYDROGRAPHIC SECTION ALONG 110W


     A.  CRUISE NARRATIVE


     A.1  HIGHLIGHTS

     Expedition Designation (EXPOCODE):  31MBEP191/1
     Chief Scientist:  Linda J. Mangum
                       NOAA Pacific Marine Environmental Laboratory
		       7600 Sand Point Way NE
		       Bin C15700 R/E/PM
		       Seattle, WA  98115-0070
		       Telephone:  (206)526-6740
	               Telefax:  (206)526-6744
		       Internet:  mangum@noaapmel.gov
     Ship:  NOAA Malcolm Baldrige, R-103
     Ports of Call:  Rodman Naval Base, Panama to Honolulu, Hawaii
     Cruise Dates:  March 23 to April 19, 1991

     Expedition Designation (EXPOCODE):  31DSEP391/1
     Chief Scientist:  Linda J. Mangum
                       NOAA Pacific Marine Environmental Laboratory
		       7600 Sand Point Way NE
		       Bin C15700 R/E/PM
		       Seattle, WA  98115-0070
		       Telephone:  (206)526-6740
	               Telefax:  (206)526-6744
		       Internet:  mangum@noaapmel.gov
     Ship:  NOAA Discoverer, R-102
     Ports of Call:  Seattle, Washington to Honolulu, Hawaii
     Cruise Dates:  October 15 to November 13, 1991


     A.2  CRUISE SUMMARY

     Cruise Tracks

          Figure 1 shows the cruise track and CTD/rosette station locations 
     for 31MBEP191/1.  Figure 2 shows the cruise track and CTD/rosette station
     locations for 31DSEP391/1.

     Number of Stations

          A total of 21 CTD/rosette profiles were collected on leg 1 of the
     spring EPOCS cruise (31MBEP191/1) using a Neil Brown Mark IIIb CTD 
     equipped with a Beckman oxygen sensor, and General Oceanics 12 bottle 
     rosette equipped with 12 10-liter Niskin water sample bottles.  Thirteen
     of the 21 profiles were collected along 110W from 5S to 5N.  

          Twenty-six CTD/rosette profiles were collected on leg 1 of the fall
     EPOCS cruise (31DSEP391/1) using a Neil Brown Mark IIIb CTD, and General 
     Oceanics 12 bottle rosette equipped with 12 10-liter Niskin water sample 
     bottles.  Fourteen of the 26 profiles were collected along 110W from 5S 
     to 10N. 

     Sampling

          Usually 8 of the 12 Niskin water sample bottles were sampled for 
     salinity and dissolved oxygen analysis each cast during 31MBEP191/1,
     with a duplicate salinity sample taken from the deepest bottle to 
     monitor the drift of the Autosal instrument.  Nominal sampling depths 
     were 1000, 900, 800, 700, 500, 250, 100, and 0 meters.  Fifteen casts 
     were to a depth of 1000 meters, 3 casts were to within 200 meters of
     the bottom, and 3 casts were to 500 meters.

          During 31DSEP391/1, all 12 Niskin bottles were sampled for salinity
     each cast, with a duplicate salinity sample taken from the deepest 
     bottle to monitor the drift of the Autosal instrument.  Nominal sampling
     depths were 1000(2), 900, 800, 700, 600, 500, 400, 250, 100, and 0(2) 
     meters.  Twenty casts were to a depth of 1000 meters, 3 casts were to 
     within 200 meters of the bottom, and 3 casts were to 500 meters.

          Bottle sample depths for 31MBEP191/1 and 31DSEP391/1 are shown in 
     figures 3 and 4, respectively.  

     Floats and Drifters

          Five AOML satellite tracked surface drifting buoys (Low Cost
     Tropical Drifters) were deployed during 31MBEP191/1 at 6N, 85W; 6.3N, 
     90W; 6N, 95W; 0N, 110W; and 0N, 125W.  Six AOML drifting buoys were 
     deployed during 31DSEP391/1 at 2N, 0N, and 2S along 110W, 2S and 0N 
     along 125W, and at 0N, 140W.

     Moorings

          Three ATLAS moorings were recovered and redeployed along 110W at 5N,
     2N, and 5S during 31MBEP191/1 and a new mooring deployed at 0N, 125W.
     Visual inspections were made of an ATLAS mooring at 2S, 110W and a current
     meter mooring at 0N, 110W.  Both moorings looked fine with no signs of
     vandalism.

          Beginning 31DSEP391/1, a pressure/temperature gauge (PTG) was
     recovered and deployed in approximately 110 feet of water off Clipperton
     Island at approximately 10N, 110W.  ATLAS moorings were deployed at 8N 
     (new site), 2N (redeployment), and 2S (recovery and redeployment) along 
     110W.  ATLAS moorings at 5N and 5S were inspected and found to be in good
     condition.  ATLAS moorings were also deployed at new sites at 5S and 2S 
     along 125W and the ATLAS mooring at 0N, 125W was visited.  Equatorial 
     current meter moorings were recovered and redeployed at 110W and 140W.
     

     A.3  LIST OF PRINCIPAL INVESTIGATORS
     	
          Dr. Stan Hayes, NOAA/PMEL	  ATLAS moorings, CTD 
          Dr. Mike McPhaden, NOAA/PMEL    current meter moorings
          Dr. Dave Behringer, NOAA/AOML   drifting buoys
          Dr. Don Hansen, NOAA/AOML	  drifting buoys
	  Dr. David Ainley, PRBO	  bird observations

     Abbreviations
          NOAA  National Oceanic and Atmospheric Administration
	  PMEL  Pacific Marine Environmental Laboratory, Seattle, WA
	  AOML  Atlantic Oceanographic and Meteorological Laboratory, Miami, FL
	  PRBO  Point Reyes Bird Observatory, Point Reyes, CA


     A.4  SCIENTIFIC PROGRAMME AND METHODS

          The NOAA-sponsored EPOCS research program is designed to further
     understanding of the role of the tropical ocean in modifying the world's
     climate.  A primary goal of this research is to investigate the dominant
     mechanisms that produce large scale, interannual variations of sea surface
     temperature in vast regions of the tropical Pacific Ocean.  Studies
     indicate that such sea surface temperature anomalies are linked to
     perturbations in the mid-latitude atmospheric pressure fields and hence
     to weather.

          Ocean currents play an important role in determining the local 
     temperature change through heat advection.  Therefore, an associated goal
     of the program is to study the horizontal, vertical and temporal varia-
     tions of the currents and how they are affected by the wind field.  
     Variability in currents, temperature, and winds are studied using numerous
     techniques including current meter moorings, thermistor chain moorings
     (ATLAS), underway acoustic doppler current profiling (ADCP), CTD profiles,
     drifting buoys, and other shipboard physical oceanographic and meteor-
     ological measurements.

          The primary objectives of 31MBEP191/1 and 31DSEP391/1 cruises were
     to maintain the array of near-equatorial ATLAS and current meter moorings 
     along 110W and 125W in the eastern tropical Pacific, and to conduct 
     hydrographic measurements in the area.  

          Temperature and salinity sections along 110W for 31MBEP191/1 (figures
     5 and 6) show a strong equatorial undercurrent in the upper 100 meters 
     between 1S and 1N, with the 25C isotherm breaking the surface near the 
     equator.  The two subsurface countercurrents are evident between 3 and 5 
     degrees on either side of the equator.  Strong westward flow of the South
     Equatorial Current is seen off the equator.  An oxygen section for 
     31MBEP191/1 is given in figure 7.  Temperature and salinity sections along
     110W for 31DSEP391/1 (figures 8 and 9) show warm water throughout the 
     section, with surface water warmer than 25C north of 2N and a well-
     developed thermocline deeper than usual, with the 15C isotherm deeper than
     100 meters equatorward of +/- 3.  The equatorial undercurrent appears well
     developed near the equator.  

          Figures 10 and 11 show the TS relationship between CTD casts taken
     along 110W during 31MBEP191/1 and 31DSEP391/1, respectively.  Salinity 
     sample data are overplotted on each.  Figure 12 shows CTD oxygen along
     110W for 31MBEP191/1 with dissolved oxygen sample data overplotted.

          A description of the methods of measurement, calibration and proces-
     sing of the NBIS CTD/O2 data is given in section C.3 of this report.


     A.5  PROBLEMS ENCOUNTERED ON THE CRUISE

          Most shipboard equipment worked well throughout 31MBEP191/1, 
     although the thermosalinograph stopped working on April 16 when the 
     VAX DECServer failed.  There were no rosette misfires noted during the 
     cruise, however the 500 meter bottle for cast 11 at 1S, 110W did not 
     close and no samples were collected.  Also, the first 42 meters of data 
     for cast 11 were lost due to operator error.

          During 31DSEP391/1, the CTD conducting cable was reterminated prior 
     to cast 13 at 5S, 110W due to intermittent spiking in the pressure channel
     and a broken strand on the outer armour about 5 meters above the mechanical
     termination.  After the cable was reterminated, no further problems were 
     observed.  All other shipboard equipment worked well throughout the cruise.


     A.6  OTHER INCIDENTS OF NOTE


     A.7  LIST OF CRUISE PARTICIPANTS

     31MBEP191/1
          Ms. Linda Mangum, NOAA/PMEL    Chief Scientist, ATLAS moorings, CTDs
	  Mr. John LoConte, NOAA/PMEL    ATLAS moorings
	  Mr. Doug Fenton, NOAA/PMEL	 current meter moorings
	  Mr. Dennis Holzer, NOAA/PMEL   current meter moorings
          Mr. Larry Spear, PRBO		 bird observations
	  Ms. Nina Karnovsky, PRBO	 bird observations
	  Mr. Phil Henderson, PRBO	 bird observations

     31DSEP391/1
          Ms. Linda Mangum, NOAA/PMEL    Chief Scientist, ATLAS moorings, CTDs
          Mr. David Root, NOAA/PMEL      ATLAS moorings
          Mr. Doug Fenton, NOAA/PMEL     current meter moorings
	  LT. Dave Zimmerman, NOAA/PMEL  current meter moorings
          Mr. Larry Spear, PRBO	         bird observations
          Mr. Ian Gaffney, PRBO          bird observations


     B.  UNDERWAY MEASUREMENTS

     
     B.1  XBT

          XBT measurements were made in accordance with SEAS instructions
     (5.2.1).  XBT data was collected and transmitted via the ship's SEAS
     unit.  For each XBT cast, the following information was recorded on log
     sheets:  wind direction, wind speed, barometric pressure, air temperature,
     bucket temperature, intake temperature, time, and ship's position.  
     

     B.2  ADCP

          A ship-mounted ADCP system was used to continuously measure the 
     currents in the upper ocean along each trackline.  Ship personnel
     operated the ADCP system and continuously logged data during the entire 
     cruise.  The NOAA ship Malcolm Baldrige provided a fully operational 
     Magnavox 1102 TRANSIT/GPS navigator with an atomic frequency standard
     integrated into the ship's Scientific Computer System (SCS) data 
     collection system.  For backup navigation, the ship provided a Magnovox
     1105 OMEGA/TRANSIT satellite navigator with a remote ship speed input.
     The SCS data acquisition and logging system has become the sole method 
     of logging navigation data on the NOAA ship Malcolm Baldrige and was 
     fully operational at all times.

          Aboard the NOAA ship Discoverer, the ADCP was interfaced with a
     Magnavox GPS navigator and received data at 2 second intervals through
     the selection of code 208, data control option 1.  Intermittent problems 
     with the gyro during 31DSEP391/1 eventually resulted in the loss of the 
     gyro on November 4th for the remainder of the cruise.  This impacted ADCP
     operations as no data were collected for the period that the gyro was 
     down due to problems interpreting the data without the gyro input.


     B.3  SST AND SSS

          Near sea surface temperature (SST) and salinity (SSS) measurements 
     were recorded continuously each cruise using a thermosalinograph.  A
     bucket sample was collected with each XBT and the record annotated by 
     date/time group and bucket temperature.  Bucket samples were also taken 
     hourly while underway during daylight hours and analyzed for SST and SSS.


     B.4  STRUCTURE OF EQUATORIAL SEABIRD COMMUNITIES (L. Spear)

          Seabird observations were conducted from the flying bridge during 
     daylight hours while the ship was underway.  While the ship was stopped
     for mooring/CTD operations, PRBO scientists could be launched in the 
     ship's Zodiak at the discretion of the Commanding Officer to collect 
     samples.

          The goals of this piggyback project were to relate seabird species 
     assemblages to water masses in the eastern tropical Pacific, and to 
     analyze patterns in distribution and ecology of these avifaunas in order 
     to reveal structuring factors.  Main activities included:  1) censusing 
     seabirds to determine each species density, patchiness, and associations
     with other species and with foraging opportunities presented by predatory
     fish, 2) gathering data on sea surface temperature, salinity, depth and 
     slope of the thermocline for each census period; 3) collecting seabirds 
     for diet analysis and measurement of aerodynamic morphology; and 4) 
     photographing seabirds for visual aid in the presentation of results.

          During 31MBEP191/1, 425 half-hour transects were conducted and 37 
     specimens of 5 major species at four locations were collected.  Also,
     three neuston tows and one bongo tow were completed for the collection
     of 17 samples for use in seabird diet analysis.  During 31DSEP391/1, 360 
     half-hour transects were conducted within 20 degrees latitude of the 
     equator, 20 specimens of 5 major species at two locations were collected,
     and 5 rolls of 36-exposure film were exposed at four other locations.


     C.  DESCRIPTION OF MEASUREMENT TECHNIQUES AND CALIBRATIONS


     C.1  SAMPLE SALINITY MEASUREMENTS

          The salinity analysis of samples was carried out exclusively on
     Guildline Autosal salinometers (model 8400A).  The instruments were
     operated in the ship's constant temperature laboratory at a bath 
     temperature of 24C.  Standardization was effected by use of IAPSO 
     Standard Seawater batch P1??.  The commonly accepted precision of the 
     Autosal is 0.001 psu, with an accuracy of 0.003 psu.  The Autosals
     were standardized before and after each run.  The drift during each run 
     was monitored and individual samples were corrected for the drift during 
     each run by linear interpolation.  Bottle salinities were compared with 
     computed CTD salinities to identify leaking bottles, as well as to 
     monitor the conductivity sensor performance and drift.


     C.2  SAMPLE OXYGEN MEASUREMENTS

          240 bottle oxygen samples were taken in calibrated clear glass
     bottles during 31MBEP191/1.  Analysis followed the Winkler whole bottle 
     method.  Dissolved oxygen measurements were not made on 31DSEP391/1.


     C.3  CTD MEASUREMENTS

     Equipment

          The spring EPOCS cruise (31MBEP191/1) underwater package was 
     comprised of a Neil Brown Mark IIIb CTD equipped with a Beckman oxygen 
     sensor, a General Oceanics 12 bottle rosette, 12 10-liter Nisken water 
     sample bottles, and a Benthos 12 kHz pinger mounted on a 12-bottle frame 
     low and opposite the CTD sensors.  A .322 inch diameter conducting cable 
     was used on an Interocean winch to lower and raise the package at typical
     rates of 30 m/min from 0-50 m, 45 m/min from 50-200 m, 60 m/min greater 
     than 200 m, and a maximum of 50 m/min during the upcast.  Data from the 
     underwater unit was transmitted in real time to a shipboard data terminal
     through the 3-conductor electro-mechanical cable in TELETYPE (TTY) format
     using a frequency shift key (FSK) modulated signal superimposed on the 
     DC power supplied to the underwater unit.  A Neil Brown Mark III deck 
     unit received the data at 5000 baud, demodulated and converted it to a
     9600 baud RS-232 serial compatible data stream.  As a backup, the original
     audio FSK CTD data signal was recorded on video cassette tapes.  A General
     Oceanics rosette 1015 deck unitwas used to close the water sample bottles.
   
          A similar underwater package was used during the fall EPOCS cruise 
     (31DSEP391/1), however there was no oxygen sensor installed on the CTD.  
     Like cable was used on a Markey winch with the same typical lowering 
     rates.  
     
     Standards and Pre-cruise Calibrations

          The EG&G conductivity sensor has a range of 1 to 65 mmho, an 
     accuracy of +/- 0.005 mmho, resolution of 0.001 mmho, and stability
     of 0.003 mmho/month.  The Rosemount platinum thermometer has a range  
     of -32 to 32 C, an accuracy of +/-0.005 C (-3 to 32 C), resolution of 
     0.0005 C, and stability of 0.001 C/month.  The Paine pressure sensor has 
     a range of 0 to 6500 db, an accuracy of +/- 6.5 db, resolution of 0.1 db,
     and stability of 0.1%/month.  

          Pre-cruise calibrations for 31MBEP191/1 Neil Brown Mark IIIb CTD
     s/n 2769 were completed on March 8, 1991 at Woods Hole Oceanographic 
     Institution, Woods Hole, Massachusetts (Millard and Yang, 1993).  CTD 
     s/n 2769 is owned by AOML.  The following calibration coefficients for 
     conductivity, temperature, and pressure were determined:

          C = 0.9995477 * C raw + 0.038996
          T = 1.0001479 * T raw + 0.000917
          P = -0.518997e-06 * P raw **2 + 1.00317 * P raw + 0.746095

          Pre-cruise calibrations for 31DSEP391/1 Neil Brown Mark IIIb CTD
     s/n 1111 were completed on September 10, 1991 at Northwest Regional
     Calibration Center (NRCC) in Bellevue, Washington.  CTD s/n 1111 is
     owned by PMEL.  The following calibration coefficients for conductivity, 
     temperature, and pressure were determined:

          C = 0.9997923 * C raw + 0.0068
	  T = 1.0003010 * T raw + 0.0538
	  P (increasing) = -0.1657277e-09 * P raw **3 + 0.151795e-05 * 
	    P raw**2 + 0.9971329 * P raw - 34.7978
	  P (decreasing) = -0.3257910e-09 * P raw **3 + 0.316872e-05 * 
	    P raw**2 + 0.9931632 * P raw - 35.4661

     CTD Data Capture and Reporting

          Aboard the Malcolm Baldrige, CTD/O2 data were collected using the
     shipboard Scientific Computer System (SCS) and AOML LOGGER software.
     Preliminary processing and calibration of the CTD/O2 data were accomp- 
     lished at sea using the shipboard microVAX system and PMEL programs.  

          Aboard the Discoverer, NBIS CTD data were collected using a 286-AT 
     personal computer equipped with EG&G Oceansoft, NBIS Mark III CTD
     acquisition software.  PMEL microVAX computers and programs were aboard 
     the Discoverer for preliminary processing and calibration of NBIS data 
     at sea.

     Conductivity Calibration

          31MBEP191/1 data files were restored to the VAX computer system at 
     PMEL from Exabyte 8mm tapes.  A calibration (.CAL) file was created at
     sea using the program CALDSK, which asks the user for CTD values at the 
     time of sample bottle closures from handwritten cast logs completed
     during acquisition and sample salinity values received from ship's survey.
     Programs LINCALW and CALMSTRW, and plotting command files CALMCONW and 
     CALMDEEPW were used to find the best calibrations to apply to this data 
     set (program descriptions are given below).  Neither pre-cruise calibra-
     tion coefficients or an overall linear least squares fit were satisfactory.
     A cast break was apparent between casts 15 and 16, corresponding to a two
     day break in CTD operations between the end of the 110W line and the 
     beginning of the 125W line.  Final calibration coefficients applied to CTD
     conductivity were the results of linear least squares fits computed for 
     each group:

          Casts 1-15 (110W line):  bias = 5.3587079E-02  
				   slope = 0.9987972    
				   std dev = 9.1723865E-03

	  Casts 16-21 (125W line):  bias = 5.9156708E-02  
				    slope = 0.9984679    
				    std dev = 7.7077947E-03

     In addition to the above conductivity calibrations, a salinity offset of 
     -.010 psu was applied to part or all of the downcasts of casts 15, 16, 
     and 17 (see CTD Data Processing section below).

          The 31DSEP391/1 calibration (.CAL) file was created at sea using
     program CALDSKW, CTD values at the time of sample bottle closures from 
     handwritten cast logs completed during acquisition, and sample salinity 
     values received from ship's survey.  Where CTD and bottle salinities 
     differed greatly, a 60 scan average salinity value output by EG&G 
     Oceansoft bottle file (.BTL) replaced the cast log value if it lessened
     the discrepancy.  Programs LINCALW and CALMSTRW, and plotting command 
     files CALMCONW and CALMDEEPW were used to find the best calibrations to 
     apply to this data set (program descriptions are given below).  Final 
     calibration coefficients applied to CTD conductivity were the results of 
     a linear least squares fit to all bottles, all casts.

          Casts 0-25 (all stations):  bias = 1.0341031E-02
                                      slope = 0.9995004    
                                      std dev = 2.7981878E-03

     Conductivity Calibration Programs and PPLUS Command (.PPC) Files

          CALDSKW creates .CAL raw data file of CTD observations at the time 
            of bottle closures and analyzed water sample values.
          LINCALW reads .CAL raw data file (may be broken into groups), 
            computes a linear least squares fit to CTD-bottle conductivity
            data, applies the model coefficients, discards observations 
            greater than 2.8 times the standard deviation, then refits the
            remaining data.  The process continues until no further 
            observations are rejected.  LINCALW writes .COEF file containing 
            model coefficients and .LOG file.  Water sample conductivity
            is obtained using the FORTRAN routine SAL78 described by Fofonoff
            and Millard (1983).
          CALMSTRW reads .CAL raw data file; applies pressure and temperature
            calibrations; corrects raw conductivity for cell material 
            deformation according to:

		C = C raw [1 + alpha(T-T0) + beta(P-P0)]	    	

            where alpha=-1.6e-06, beta=1.5e-08, T0=15, and P=3; applies 
            conductivity calibrations; writes .CLB calibrated data file and
            .SEA calibrated data file in WOCE format.
          CALMCONW.PPC reads .CLB calibrated data file and makes five plots
            of discrete measurements:  P, T, C, S, and cast number verses
            CTD-bottle conductivity.  These are examined for cast breaks and
            drifts in the CTD.
          CALMDEEPW.PPC reads .CLB calibrated data file and makes two plots: 
            CTD salinity and bottle salinity verses potential temperature from
            theta = 0.6 to 2.2 C.

     Temperature Calibration

          Pre-cruise calibrations were the only corrections applied to 
     temperature measurements collected on both cruises.  Temperature 
     measurements, calibrations, and computation of derived oceanographic 
     variables used the 1968 temperature scale.  Temperatures were converted 
     to the ITS90 scale for WOCE reporting according to:

          T68 = 1.00024 * T90

     as suggested by Saunders (1990):

     Pressure Calibration

          Pre-cruise calibrations were the only corrections applied to
     pressure measurements collected on both cruises.  

     Oxygen Calibration

          The oxygen model has the following forma (Owens and Millard, 1985):

          OX = A * (OXC+B*dOXC+C) * EXP(D*(T+E*(OXT-T))+F*P) * OXSAT(S,T)

     where A is the slope, B is the time constant for oxygen diffusion through
     the membrane, C is the oxygen current bias, D is a temperature correction,
     E is the weighting factor of oxygen sensor and water temperatures, F is
     the pressure correction, and OXSAT(S,T) is the oxygen saturation value
     after Weiss, 1970.

          The coefficients of the oxygen model are computed in program POXFITW
     which reads a .CLO file of downtrace CTD data records matched according to
     temperatures in the uptrace .CAL file by program OXDWNW, and minimizes
     the difference between CTD and bottle oxygens by varying the 6 parameters
     using the same least squares polynomial subroutine as LINCALW in fitting
     conductivities.  One overall (casts 1-21) non-linear fit was made to 
     31MBEP191/1 oxygen data with the following results:

          A = 2.404		standard deviation = 0.12223
          B = 2.077		number of observations = 150
          C = 0.023 		dox = 0.342
          D = -0.02794
          E = 1.469
          F = 0.1504e-03
	  
     CTD/bottle oxygen variance with pressure was unfortunately large.

          Oxygen calibrations were applied to the bottle data (.CLB) using 
     CALMSTRW and to CTD data files using EPCTDW.  Nearly every cast had 
     oxygen spikes around 200 db.  All but casts 1, 3, and 4 had spikes 
     removed, most of which were removed using NOMIT in EPCTDW.  Casts 10, 15,
     16, 17, 19, and 20 had sections around 200 db interpolated using EPIC
     (Soreide and Hayes, 1988) utility CTDINTERP.

     Oxygen Calibration Programs and PPLUS Command (.PPC) Files 

          OXDWN2W reads .CAL raw data file and DLAGAVZ .CTD ASCII data files
            (see CTD Processing Programs), extracts down profile data record
            including oxygen current and oxygen temperature at calibrated CTD 
            temperatures corresponding to the upcast bottle levels, computes
            CTD oxygen and oxygen saturation, and writes a .CLO data file.
          POXFITW reads .CLO data file, fits the coefficients of the oxygen
            model using a non-linear regression technique varying 6 parameters,
            and writes .PAR listing of the final coefficients and .REJ file of
            those scans where the CTD/bottle oxygens differed by more than 2.8
            times the standard deviation throughout all iterations.
          CALOX2W reads the .PAR values and .CLO data, applies the calibration
            coefficients, and writes a calibrated .CLO file.  
          DOX.PPC makes plots of CTD oxygen verses bottle oxygen; and cast
            number, pressure, and temperature verses CTD-bottle oxygen to
	    verify calibration coefficients applied.

     CTD Data Processing

          31MBEP191/1 files were restored from Exabyte 8mm tapes to the VAX
     at PMEL.  Files produced at sea using DPDNZ and DLAGAVZ programs were
     retained.  The minimum fall rate acceptable in DLAGAVZ was 0.5 db/60 
     scans and the pressure interval to skip after a fall rate failure was 
     1.2 db.  EPCTDW apllied conductivity and oxygen calibrations to the 
     1-meter averaged data set. 

          DEEPCTD, FULLTS, and density plots were looked at for any single 
     point spikes, looping, or intermittent salinity offsets.  Casts 6, 9,
     10, 18, and 20 were despiked using EPCTDW subroutine NOMIT.  Cast 15 
     displayed an offset in salinity between 485 db and 1009 db owing to 
     possible sensor fouling.  Program S_OFFSET.FOR was written to apply a
     correction of -0.040 psu to salinity in this area.  Cast 16 showed some 
     spiking in salinity and an immediate offset in salinity from 784 db to 
     1005 db.  The offset was seen in the upcast and in the downcast of cast 
     17.  S_OFFSET.FOR also applied a correction of -0.010 psu to the end of 
     cast 16 and to all of cast 17.  No offset was seen in cast 18.  EPIC 
     utility CTDINTERP linearly interpolated salinity between 740 db and 784 
     db of cast 16 to remove the interference.

          FULLTS and density plots also revealed an anomalous jump in salinity
     for casts 1, 2, 6, 7, and 21.  In all cases, salinity decreased by
     approximately 0.037 psu over 1 db change in pressure somewhere between 
     300-500 db.  The offset occurred during the downcasts only and the deeper
     bottles matched well with the CTD trace.  Since density profiles showed 
     no instability in the water column above the jumps, there was no straight-
     forward way to correct for the offsets.  They are noted here and a 
     warning line included in the cast headers.
     
          31DSEP391/1 processing took place at sea.  The following standard 
     processing programs and PPLUS (Denbo, 1992) command files were used to
     process the data.  TSPLTEP and 3PLTNOX plots were looked at for any 
     additional spiking but none were noted.

     CTD Data Processing Programs and PPLUS Command (.PPC) Files

          DPDNZ reads a raw CTD data file, computes a running fall rate over
            +/- 30 scans, and writes all data to a binary (.DPZ) file and an
            ASCII (.RECZ) file.  A record range for the downcast is determined
            from the .RECZ file.
          DLAGAVZ reads .DPZ file, applies precruise calibrations, edits data 
            for window outliers and first differencing outliers, fills gaps 
            by linear interpolation, lags conductivity according to:

	         C(I) = (1-A) * C(I) + A * C(I-1)

            where C is calbrated conductivity and A=.87, flags data exceeding 
            fall rate criteria (default minimum fall rate acceptable is 0.8 
            db/60 scans (25 meters per minute) and pressure interval of 1.5 
            db), and computes 1-meter averages.  DLAGAVZ writes an error file 
            of outlier flags, interpolated values, and fall rate criteria 
            failures; and an ASCII .CTD data file including computed salinity 
            values.
          EPCTDW reads .CTD file of calibrated P, T, OXC, OXT, and CR (lagged
            but uncalibrated conductivity); applies any additional P and T 
            calibrations, corrects conductivity for cell material deformation:

                 C = CR*(1-alpha(T-15)+beta(P/3))	    	

            where alpha=6.5e-06 and beta=1.5e-08, and applies conductivity 
            calibrations.  EPCTDW computes salinity, applies calibrations to 
            oxygen when available, has an option to eliminate 1-point spikes 
            according to the gradients restrictions given in the source code 
            (not used by default), omits additional spikes as specified in the
            command file, fills data by linear interpolation for a value to 
            exist every whole meter, recomputes conductivity from salinity, 
            and calculates other oceanographic variables.  EPCTDW writes the
            final .CTD data file in EPIC format, and a .LOG file of editted 
            and filled data points.
          EPICBOMSTRW reads .CLB calibrated bottle data file and .CTD EPIC 
            data files (for header information) and writes final .BOT bottle 
            data files in EPIC format.
          DEEPCTD.PPC reads .CTD EPIC pointer file and .BOT EPIC pointer file
            of deep casts only and overplots discrete bottle salinity data on
            the CTD salintiy trace from theta=0.8 to 2.4 C.
          FULLTS.PPC reads .CTD EPIC pointer file and .BOT EPIC pointer file 
	    and overplots bottle and CTD salinity data from theta = 0 to 30 C 
            for each cast.
          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 for each profile.  TSPLTB.PPC is used to 
            include oxygen data.  
          TEXTNOX reads .CTD EPIC pointer file and writes a PPLUS command
            file containing label commands for table listings of subsampled
            CTD data for each cast to be used with 3PLTNOX.
          3PLTNOX.PPC reads TEXTNOX output and .CTD EPIC pointer file and 
            overplots profiles of temperature, salinity, and sigma-t vs. 
            pressure to 1000 db with subsampled CTD data listed in table form
            for each station.  4PLT1DB.PPC is used to include oxygen data.

     References     

     Denbo, D.W., 1992.  PPLUS Graphics, P.O. Box 4, Sequim, WA, 98382.

     Fofonoff, N.P., and R.C. Millard, Jr., 1983.  Algorithms for Computation 
          of Fundamental Properties of Seawater.  UNESCO Technical Papers in 
          Marine Science 44.

     Millard, R.C, and K. Yang, 1993.  CTD Calibration and Processing Methods
          used at Woods Hole Oceanographic Institution.  Woods Hole Oceano-
          graphic Institution Technical Report, WHOI-93-44.

     Owens, W.B., and R.C. Millard, Jr., 1985.  A New Algorithm for CTD Oxygen
          Calibrations.  Journal of Physical Oceanography, 15, 621-631.

     Saunders, P.M., 1990.  The International Temperature Scale of 1990.  
          ITS90.  WOCE Newsletter, 10, IOS, Wormley, U.K.

     Soreide, N.N., and S.P. Hayes, 1988.  A System for Management, Display,
          and Analysis of Oceanographic Time Series and Hydrographic Data.
          Fourth International Conference on Interactive Information and 
	  Processing Systems for Meteorology, Oceanography, and Hydrology.
  	  American Meteorological Society, Boston, J20-J22.

     Weiss, R.F., 1970.  The Solubility of Nitrogen, Oxygen, and Argon in Water
         and Seawater.  Deep-Sea Research, 17, 721-735.
