


     GP8-95-MB
     NOAA Ship Malcolm Baldrige
     Pago Pago, Samoa - Rodman, Panama
     December 19 - January 17, 1996

     Chief Scientist: Ms. Linda Mangum
     Survey Department: CST D. Sweeney
     CTD Personnel: Ship's Survey Department
     Final Processing: K. McTaggart, M. O'Haleck


     ACQUISITION: 

     Twenty-two CTD profiles were collected during this cruise covering two
     meridionals from 8S to 5S along 170W and 5S to 8N along 155W.  Three
     profiles were collected along 170W, and 15 along 155W.  The majority of 
     casts were to 1000 m; 3 casts were deep.  Four casts were made at 
     mooring sites enroute to Rodman at 5N, 125W, 2N, 110W, and 2N and 8N, 95W.
     
     All casts used TAO's Sea-Bird 9plus CTD s/n 09P10881-0390 measuring 
     pressure (s/n 58950), temperature (s/n 1708), and conductivity (s/n 1467).
     The CTD was mounted in AOML's 24-bottle frame with a Sea-Bird rosette 
     sampler.  The CTD data stream was passed through AOML's Sea-Bird 11plus 
     deck unit with factory settings.  An analog signal was recorded onto
     the audio portion of VCR tape as a backup.  Digitized data were sent to a
     Zenith personal computer equipped with Sea-Bird's SEASOFT acquisition 
     software (version 4.209) where calibrated data were displayed in graphical
     form in real-time, as well as stored in raw form onto the hard disk.  
     Backups of the raw data were made on 200 Mbyte Syquest tapes and returned
     to PMEL for post-cruise processing.

     There was no cast 24.  Cast 33 was replayed from VCR tape at PMEL.


     SALINITIES:

     Salinity analysis was performed using Guildline Autosal salinometer
     s/n ??? (last calibrated ???) and IAPSO standard seawater batch #P125.
     Instrument calibrations were not applied to the bottle salinities used to
     calibrate this data set, only a drift-during-run linear interpolation 
     correction.  Standard operating temperature was 24 degrees Celsius.


     POST-CRUISE CONDUCTIVITY CALIBRATIONS:

     GP7-895A.CAL was created at PMEL using program SBECAL.  Anomalous 
     differences between CTD and bottle salinities were scrutinized.
     Bottle salinities were checked against their original log sheets 
     for typos.  

     Final pressure and temperature calibrations were pre-cruise.  
     Conductivity calibration coefficients were best determined using a 
     station-dependent linear fitting routine, CALCOS1, written by 
     Greg Johnson in MATLAB for three groups of casts.

     	Casts 1-17:  total number of points = 231
		     % pts used in fit = 83.12
	    	     fit standard deviation = 0.003314
		     fit bias = 0.0031766107
		     min fit slope = 1.000352
		     max fit slope = 1.000414

     	Casts 18-33: total number of points = 226
		     % pts used in fit = 95.13
	    	     fit standard deviation = 0.001368
		     fit bias = 0.0062562787
		     min fit slope = 1.000090
		     max fit slope = 1.000164

     	Casts 34-37: total number of points = 47
		     % pts used in fit = 95.74
	    	     fit standard deviation = 0.0009389
		     fit bias = 0.0022208026
		     min fit slope = 1.000339
		     max fit slope = 1.000344

     Slope and bias values were applied to CTD data using PMEL Fortran program 
     GP895_EPIC; and to bottle files using CALMSTR7.


     FINAL PROCESSING:

     The following are the standard SEASOFT processing modules used to
     reduce Sea-Bird CTD data:

     DATCNV converts raw data to engineering units and creates a bottle
     file if a Sea-Bird rosette sampler was used.  (MARKSCAN creates a 
     bottle file if a General Oceanics rosette was used.)

     ROSSUM averages the bottle data specified in the DATCNV or MARKSCAN
     output and derives salinity, theta, sigma-t, and sigma-th.  These
     bottle files are transfered to the PMEL VAX where post-cruise 
     calibrations are computed.

     WILDEDIT makes two passes through the data in 100 scan bins.  The
     first pass flags points greater than 2 standard deviations; the
     seond pass removes points greater than 20 standard deviations from
     the mean with the flagged points excluded.

     CELLTM uses a recursive filter to remove conductivity cell thermal
     mass effects from the measured conductivity.  In areas with steep
     temperature gradients the thermal mass correction is on the order
     of 0.005 psu.  In other areas the correction is negligible.  The
     value used for the thermal anomaly amplitude (alpha) is 0.03.  The
     value used for the thermal anomaly time constant (1/beta) is 9.0.
 
     FILTER applies a low pass filter to pressure with a time constant of
     0.15 seconds, and to conductivity with a time constant of 0.03 seconds.
     In order to produce zero phase (no time shift) the filter is first
     run forward through the file and then run backwards through the file.

     LOOPEDIT removes scans associated with pressure slowdowns and
     reversals.  If the CTD velocity is less than 0.25 m/s or the pressure
     is not greater than the previous maximum scan, the scan is omitted.

     BINAVG averages the data into 1 db bins.  Each bin is centered around
     a whole pressure value, e.g. the 1 db bin averages scans where pressure
     is between 0.5 db and 1.5 db.

     DERIVE uses 1 db averaged pressure, temperature, and conductivity to
     compute salinity, theta, sigma-t, sigma-th, and dynamic height.

     SPLIT removes decreasing pressure records and keeps only the downcast
     data.

     TRANS converts the data file from binary to ASCII format.  These 
     data are transfered to the PMEL VAX.

     PMEL program GP895_EPIC applies post-cruise conductivity calibration 
     coefficients, recomputes the derived variables in DERIVE, and converts
     the ASCII data files to EPIC format.  Sea-Bird .CNV files are editted 
     to remove bad records near the surface (typically the top 4 m) and any 
     causing spikes in the deeper water column before running GP895_EPIC.
     GP895_EPIC extrapolates raw data to the surface (0 db) within 10 db.  
     Because the SBE module LOOPEDIT does not handle package slowdowns and 
     reversals well in the thermocline where gradients are large, GP895_EPIC 
     removes raw data records where a sigma-theta inversion is greater than 
     -0.01 kg/m3.  Data are linearly interpolated such that a record exists
     for every 1 db.  When data are interpolated over greater than 2 db, the 
     WOCE quality word is '666'.

     PMEL program CALMSTR7 applies post-cruise conductivity calibration
     coefficients and recomputes the derived variables in ROSSUM.  EPICBOMSTR24
     converts the ASCII bottle data file into individual cast EPIC data files.
     Bad bottles that were not included in EPIC bottle files were cast 26
     bottle 9.

     Final CTD and bottle files were moved to DISK$EPIC1:[HAYES.DATA] and 
     included in the RIM data management tables on August 20, 1996.  
