


     GP2-01-KA
     NOAA Ship Ka'imimoana
     San Diego, CA - San Diego, CA
     March 28 - May 4, 2001

     Chief Scientist: Mr. Dave Zimmerman
     Survey Department: ST Amy Frank 
     CTD Personnel: ST Amy Frank
     Final Processing: K. McTaggart


     ACQUISITION: 

     Thirty-nine CTD profiles were collected on this cruise.  Twenty-six
     profiles were collected along the ship's trackline from 12N to 8N
     and along 110W from 8N to 8S, and thirteen profiles were collected
     along 95W from 5S to 12N.  Two casts were deep (3000 m) and the rest
     were to 1000 m.  There was one TC module calibration cast to 400 m
     at station 32.  This cast was not processed as part of this data set.

     PMEL's Sea-Bird 9plus CTD s/n 09P10881-0390 measuring pressure (s/n 
     58950), the ship's temperature (s/n 2027, 2026), and the ship's 
     conductivity (s/n 1537, 1536) was used for 37 casts (PMC24.CON, 
     sensors yearly calibrated prior to this cruise).  The primary sensor
     pair was swapped out with TAO sensors (s/n 1710, 1469) for 3 casts
     in an effort to troubleshoot modulo errors, which turned out to be 
     the winch slip rings replaced May 8, 2001.

     The CTD was mounted in a custom 24-bottle frame with Sea-Bird rosette 
     sampler s/n 88.  The CTD data stream was passed through Sea-Bird 11plus
     deck unit s/n 376 with factory settings.  An analog signal was recorded 
     onto the audio portion of VCR tape as a backup.  Digitized data were sent
     to a Dell 5133 personal computer equipped with Sea-Bird's SEASOFT 
     acquisition software (version 4.216) where calibrated data were displayed 
     in graphical form in real-time, as well as stored in raw form onto hard 
     disk.  Backups of the raw data were made on QIC-80 1/4" cartridge tapes 
     and returned to PMEL for post-cruise processing.  Cruise data were also
     archived on 8 mm tape and CD-ROM.

     Cast 4 and 17 were cancelled due to modulo errors and the data lost.

  
     SALINITIES:

     Seawater was collected at 12 depths each cast and salinity samples drawn.
     Two salinity samples were taken from the deepest Nisken.  Duplicate samples
     were analyzed on a subsequent day from the rest.  Salinity analysis was
     performed using Guildline Autosal 8400B salinometer s/n 61.667.  IAPSO 
     standard seawater batch #P139, was used for all casts.  Laboratory 
     operating temperature ranged from 22.8-25.1 degrees Celsius, depending 
     on the session.


     POST-CRUISE CONDUCTIVITY CALIBRATIONS:

     GP201S.CAL of primary sensor data (not including any duplicate salts)
     was created at sea.  It's completeness and correctness were scrutinized
     and ammended where needed.

     The primary sensor pair for the majority of casts was the usual s/n 
     2027 and 1537.  For 3 casts the primary sensor pair was s/n 1710 and
     1469.  Final pressure and temperature calibrations were pre-cruise.
     A viscous heating correction of -0.0006 C was applied to both temperature
     sensors.  A historical drift correction of -0.000217 was also applied to
     s/n 2027.  No drift correction was applied to temperature sensor 1710.

     Conductivity fit coefficients were determined using Matlab program
     CALCOS0.  Although there were two deep stations to 3000 m, there were
     no sample data collected deeper than 1000 m so CALCOP routines were not
     considered.  However, a beta value was preset at -7.2e-07 before running
     CALCOS0 in order to align the deep theta-s with historical profiles.  
     Also, salinity analysis was poor and jumped around with each
     run owing to an inexperienced operator so station dependent and higher
     order fits were not considered.

     Casts 1-17, 21-41:  number of points used   354
                         total number of points  420
                         % of points used in fit 84.29
                         fit standard deviation  0.005776
                         fit bias               -0.0089999554
                         fit slope               1.0002644

     Casts 18-20: number of points used   22
                  total number of points  32
                  % of points used in fit 68.75
                  fit standard deviation  0.002456
                  fit bias               -0.018766755
                  fit slope               1.0009307

     Slope and bias correction values were applied to CTD data and converted
     directly into netCDF format using CNV_EPS; and to bottle file data 
     using CALMSTR and CLB_EPS. 


     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.  Both down and up casts
     are processed.

     ROSSUM averages the bottle data specified in the DATCNV output and 
     derives salinity, theta, sigma-t, and sigma-th. Bottle data are used
     to calibrate the CTD post-cruise. 

     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.

     TRANS converts the data file from binary to ASCII format.

     Program CNV_EPS applies post-cruise temperature corrections and
     conductivity calibration coefficients, recomputes the derived variables 
     in DERIVE, and converts the ASCII data files to netCDF format.  CNV_EPS
     skips bad records near the surface (typically the top 3 m) as well as any
     records containing -9.990e-29, and copies back 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, CNV_EPS 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 copied back to 
     the surface, the WOCE quality word is '888'; when interpolated over 
     greater than 2 db, the WOCE quality word is '666'.  The WOCE quality word
     consists of a 1-digit flag for pressure, temperature (ITS-90), and 
     salinity.

     Casts 0181-0221 (n=5) downcast data were bad between 0-100 db, both 
     primary and secondary data.  So the upcast was used in the final 
     processing.  Program GET_UPCAST was run on these 5 casts prior to running
     CNV_EPS.

     Program CALMSTR applies post-cruise temperature corrections and 
     conductivity calibration coefficients and recomputes the derived variables
     in ROSSUM.  CLB_EPS converts the ASCII bottle data file into individual
     cast netCDF data files.  The following sample salinities were flagged as
     bad and removed from individual bottle files:
		station  5		sample 106
			18		       108
			25		       101
			27		       101
			27		       103
			28		       104
			28		       105
 			31		       101
			37		       106
			41		       104

     Final CTD and bottle files were moved to DISK$EPIC1:[HAYES.DATA.GP201.CTD] 
     and included in the MySQL data management tables on May 24, 2001.  Ammended 
     data were copied to DH on May 29, 2001.
