



     GP4-05-KA
     NOAA Ship KA'IMIMOANA
     Kwajalein, Marshall Islands - Honolulu, HI
     July 15 - August 12, 2005

     Chief Scientist: Ben Moore
     Survey Department: ST Shawn Gendron, ST Elaine Stuart (in training)
     CTD Personnel: ST Shawn Gendron, ST Elaine Stuart
     Final Processing: K. McTaggart


     ACQUISITION: 

     Fifty CTD profiles were collected at 50 stations during this cruise.
     Twenty-three profiles were collected from 8N to 8S along 165E, and 27 
     profiles were collected from 8S to 8N along 180 and along the northern 
     trackline to 12N.  The majority of casts were to 1000m.  Six casts were
     deep (>3700m) and none were shallow.

     PMC's Sea-Bird 9plus CTD s/n 09P13807-0439 (pressure s/n 59788) was used
     for all casts during this cruise, along with primary temp sensor s/n 1710 
     and primary cond sensors s/n 524, and secondary temp sensor s/n 4211 and 
     secondary cond sensor s/n 1467.

     The CTD was mounted in the TAO spare custom 24-bottle frame with TAO SBE 
     carousel pylon s/n 54.  The CTD data stream was passed through TAO 11plus
     deck unit s/n 376 with factory settings.  Digitized data were sent
     to a new Dell personal computer using Windows XP OS equipped with SBE'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 a Sony thumb
     drive and DVD.   DVDs were returned to PMEL for post-cruise processing.


     SALINITY SAMPLES:
   
     No duplicate samples were taken this cruise.  Salinity analysis was 
     performed using Guildline Autosal 8400B salinometer s/n 61.667, Ocean
     Scientific ACI2000, and IAPSO standard seawater batch #P143 dated February
     2003.  The bath temperature was set to 24 degrees Celsius.  Only 8 samples
     are collected per cast, and no samples are collected from the half-degree 
     stations between 3N-3S.  Raw data were archived along with CTD data on CD.  

     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.

     No samples were collected on cast 0041 at 5N, 165E owing to misplaced lanyards.


     CONDUCTIVITY CALIBRATION:
   
     GP405S.CAL of primary sensor data (te 1710, co 524) was created at PMEL  
     and used to calibrate all stations 1-50.

     Final pressure and temperature calibrations were pre-cruise.  A viscous
     heating correction of -0.0006 C was applied to the temperature sensor.
     The drift correction for s/n 1710 was zero.

     The best results were from an overall fit determined by CALCOP4:

     number of points used   254
     total number of points  289
     % of points used in fit 87.89
     fit standard deviation  0.002974
     fit bias               -0.01552903
     fit co pressure fudge  -3.5904321e-007 
     min fit slope           1.000546
     max fit slope           1.0007905

     Slope and bias correction values were applied to CTD burst data using 
     CALMSTR.  Calibrated data were converted into NetCDF format using CLB_EPS 
     on PC Pacific.  Final calibrations were applied to profile data and
     converted into NetCDF format using CNV_EPS1.


     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, and sigma-theta. Bottle data are used
     to calibrate the CTD and O2 sensor 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.  Data were kept within 100
     of the mean (i.e. all data).

     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.

     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 7.0.
 
     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.  There is no surface bin.

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

     TRANS converts the data file from binary to ASCII format.

     Program CNV_EPS1 applies post-cruise temperature corrections and
     conductivity calibration coefficients, as well as any offset to salinity,
     recomputes the derived variables in DERIVE, and converts the ASCII data
     files to netCDF format.  CNV_EPS1 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_EPS1
     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.

     Nine bottles were flagged bad: station 1 sample 102, 14 105, 22 102, 28 102,
     33 101, 39 101, 45 104, and station 46 samples 101 and 103.

     Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes
     /gp405/ctd/ and /bot and included in the MySQL data management tables on
     September 13, 2005.
