


     GP2-03-KA
     NOAA Ship KA'IMIMOANA
     San Diego, CA - Manzanillo, Mexico
     March 24 - April 27, 2003

     Chief Scientist: Mr. Patrick A'Hearn
     Survey Department: ST Randy Ramey, ST David Fischman
     CTD Personnel: ST Randy Ramey, ST David Fischman
     Final Processing: K. McTaggart


     ACQUISITION: 

     Sixty-two CTD profiles were collected during this cruise.  Twenty-five
     profiles were collected along the ship's trackline from 12N to 8N and
     down 110W from 8N to 8S; and 37 profiles were collected along 95W from
     8S to 8N and along the ship's trackline from 8N to 12N.  The majority 
     of casts were to 1000m.  Seven casts were deep (>3000m) and 11 were
     shallow (<500m).

     PMC's Sea-Bird 9plus CTD s/n 09P13807-0439 measuring pressure (s/n 
     59788), temperature sensors (s/n 4211 TAO, 2126 PMC) and conductivity
     sensors (s/n 1467 TAO, 3438 PMC) were used for all casts.  The 
     secondary TC pair were chosen for calibration and processing, however 
     primary TC data were calibrated and processed for casts 0011 and 0021
     owing to a faulty secondary temperature cable.

     The CTD was mounted in the TAO spare custom 24-bottle frame with a new
     Sea-Bird carousel pylon s/n 88.  The CTD data stream was passed through
     11plus deck units, s/n 376 with factory settings.  Digitized data were sent
     to a Dell personal computer using Windows 98 OS equipped with Sea-Bird's
     SEASOFT Windows acquisition software.  Calibrated data were displayed
     in fixed listing and graphical form in real-time, as well as stored in
     raw form onto hard disk.  Backups of the raw data were made on Zip disk
     and CD and the CD was returned to PMEL for post-cruise processing.


     SALINITIES:

     No duplicate samples were taken this cruise.  Salinity analysis was performed
     using Guildline Autosal 8400B salinometer s/n 61.667, OSI ACI2000 interface,
     and IAPSO standard seawater batch #P139 dated November, 2000.  Bath 
     temperature was set to 24 degrees Celsius.  Raw data were archived on
     floppy disk and CD and returned to PMEL.

     The Autosal fan was not plugged in at the start of the first run and so the
     results for cast 0011 were poor and not used to calibrate the CTD.  Autosal
     readings were erratic and high for cast 0261 samples.  The problem was 
     resolved after restandardizing the machine.  Cast 0261 samples 1-7 were
     rerun under the new standard.  Autosal run of casts 00321-0341 was not
     standardized properly.  Data were recomputed from uncorrected readings post-
     cruise.

     At PMEL, ACI2000 .dat files were ammended in Excel such that only 1 header
     line, 1 standard correction line, and 3 salinity lines per sample were
     included in the file.  Corrected salinity values were fixed to 4 decimal
     places and the file overwritten in the NT folder as a space delimited file.


     POST-CRUISE CONDUCTIVITY CALIBRATIONS:

     GP203S.CAL of secondary sensor data was created at PMEL.  Primary data were
     not used because the residual conductivity scatter between CTD and bottles
     displayed an offset as well as a drift over the cruise.

     Final pressure and temperature calibrations were pre-cruise.  A viscous
     heating correction of -0.0006 C was applied to temperature sensor s/n 2126
     but no historical data for a drift correction are available for this sensor
     because it was borrowed from the MACARTHUR.

     Secondary conductivity fit coefficients were determined using Matlab program
     CALCOP0 for conductivity s/n 1697 also borrowed from the MACARTHUR.

			number of points used   495
			total number of points  575
			% of points used in fit 86.09
			fit standard deviation  0.003227
			fit bias                0.0043581923
			fit co pressure fudge   -5.4964165e-007
			min fit slope           0.99983471
			max fit slope           0.99983471

     Primary conductivity fit coefficients applied to casts 0011 and 0021 were
     determined using CALCOS1 for conductivity s/n 1467 (new temperature sensor
     s/n 4211).

			number of points used   493
			total number of points  580
			% of points used in fit 85
			fit standard deviation  0.003047
			fit bias                -0.0075281776
			min fit slope           1.0003347
			max fit slope           1.0005611

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

     There was no bottle file for cast 0011 or 0141.  Bad salinities were flagged
     for cast 0111 sample 109, cast 0281 sample 109, and cast 0461 sample 109.
     Flagged data are stored in gp203s_eps.clb.


     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.  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.

     The upcast was used instead of the downcast for cast 0041 because the
     downcast profile was missing 0-19 dbar.

     Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes
     /gp203/ctd/ and included in the MySQL data management tables on May 7,
     2003.
