


     GP4-99-KA
     NOAA Ship Ka'imimoana
     Kwajalein, Marshall Islands - Pearl Harbor, HI
     August 4-September 2, 1999

     Chief Scientist: Ms. Margie McCarty
     Survey Department: CST Dennis Sweeney
     CTD Personnel: D. Sweeney, M. McCarty
     Final Processing: K. McTaggart


     ACQUISITION: 

     Fifty-five CTD profiles were collected on this cruise.  Twenty-six CTD
     profiles were collected along 165E from 8N to 8S; 24 were collected
     along 180 from 8S to 8.5N, and 5 were collected along 170W from 6N to
     10N.  The majority of CTD casts were to 1000 m; 13 were deep (4000 m);
     and 4 were shallow casts to 200 m.

     The ship's Sea-Bird 9plus CTD s/n 09P10493-0405 measuring pressure (s/n 
     61183), temperature (s/n 2027, 2026), and conductivity (s/n 1537, 1536)
     was used for all casts (PMC15.CON).  Prior to this cruise, primary
     temperature sensor s/n 2026 was identified as having a much faster drift
     trajectory over the last year than the secondary temperature sensor s/n
     2027.  So primary and secondary TC pairs were swapped on the package.

     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.  TESAC messages were
     sent for each cast.


     SALINITIES:

     MBARI requests 8 bottles be tripped between 200 m and the surface.  The
     remaining 4 bottles were used for calibration purposes.  Two salinity 
     samples were taken from the deepest Niskin.  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 #P135 was used for all casts.  NRCC calibrations 
     were not applied to this data set, only a drift-during-run linear 
     interpolation correction in ship program DISAL.  Standard laboratory 
     operating temperature was approx 26 degrees Celsius.


     POST-CRUISE CONDUCTIVITY CALIBRATIONS:

     GP499S.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.

     Final pressure and temperature calibrations were pre-cruise.  Drift 
     (0.000867 C) and viscous (-0.0006 C) corrections were applied to tempera-
     ture.  Conductivity fit coefficients were determined using Matlab program
     CALCOP1:

			number of points used   430
			total number of points  549
			% of points used in fit 78.32
			fit standard deviation  0.001436
			fit bias                0.0035613864
			fit co pressure fudge   -2.6771197e-007
			min fit slope           0.99996688
			max fit slope           0.99997377

     Slope, bias, and pressure correction values were applied to CTD data using 
     PMEL Fortran program GP499_EPIC; and to bottle file data using CALMSTR4.


     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 programs GP499_EPIC applies post-cruise temperature corrections and
     conductivity calibration coefficients, recomputes the derived variables 
     in DERIVE, and converts the ASCII data files to EPIC format.  GP499_EPIC 
     skips bad records near the surface (typically the top 5 m) as well as any
     records containing -9.990e-29, and 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, GP499_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 extrapolated 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.

     PMEL program CALMSTR4 applies post-cruise temperature corrections and 
     conductivity calibration coefficients and recomputes the derived variables
     in ROSSUM.  EPICBOMSTR converts the ASCII bottle data file into individual
     cast EPIC data files.  Bad bottle salts were flagged in GP499S_EPIC.CLB 
     for station 7 sample 106 (7/106), 8/102, 13/102, and 13/102.  Station 35
     sample 105 was flagged as questionable.

     Final CTD and bottle files were moved to DISK$EPIC1:[HAYES.DATA.GP499.CTD] 
     and included in the RIM data management tables on September 21, 1999.  
