


     GP8-04-KA
     NOAA Ship KA'IMIMOANA
     Kwajalein, Marshall Is. - Honolulu, HI
     November 22 - December 18, 2004

     Chief Scientist: Ben Moore
     Survey Department: ST Shawn Gendron
     CTD Personnel: ST Shawn Gendron, Carla Engalla
     Final Processing: K. McTaggart


     ACQUISITION: 

     Fifty CTD profiles were collected during this cruise.  Twenty-three
     profiles were collected from 8N to 8S along 165E. Twenty-seven profiles 
     were collected from 8S to 8N along 180, and to 12N along the ship's
     trackline.  The majority of casts were to 1000m.  Seven casts were
     deep (>3000m).

     PMC's Sea-Bird 9plus CTD s/n 09P13807-0439 measuring pressure (s/n 
     59788), temp sensors s/n 2126 and 4211, and cond sensors s/n 524 and 1537
     were used for casts 1-37 (03Oct04.CON).  The conductivity difference
     became greater than .001 mS/cm and the primary sensor pair was swapped
     out with temp sensor s/n 1710 and cond sensor s/n 1697.  It was easier to
     swap out the TC pair than just the conductivity sensor.  The latter .CON
     file was 07Dec04.CON.

     The CTD was mounted in the TAO spare custom 24-bottle frame with TAO SBE 
     carousel pylon s/n 407.  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.


     SALINITIES:
   
     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.  This season,
     only 8 samples will be collected per cast instead of 12, and no samples
     will be collected from the half-degree stations between 3N-3S.  Raw data
     were archived along with CTD data on DVD.  

     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:
   
     GP804S.CAL of secondary sensor data (te 4211, co 1537) was created at PMEL  
     and used to calibrate all stations 1-50.  Secondary sensors were chosen
     over the primary because they are newer models and better behaved (s/n 524
     would require a beta pressure correction).  Also, there were two primary
     pairs used during this cruise.

     Final pressure and temperature calibrations were pre-cruise.  A viscous
     heating correction of -0.0006 C was applied to each temperature sensor
     but no historical data for a drift correction are available.

     The best fit was determined using CALCOS0 on the overall grouping:

        number of points used   261
        total number of points  302
        % of points used in fit 86.42
        fit standard deviation  0.003257
        fit bias                -0.011252615
        min fit slope           1.0004355
        max fit slope           1.0004355

     Slope and bias correction values were applied to CTD burst data and converted
     directly into netCDF format 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, and sigma-theta. Bottle data are used
     to calibrate the CTD sensors 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_EPS2 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_EPS2 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 15 db.
     Because the SBE module LOOPEDIT does not handle package slowdowns and
     reversals well in the thermocline where gradients are large, CNV_EPS2
     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.

     Five bottles were flagged bad: station 0191 sample 101; station 0221
     sample 101 and 104; station 0231 sample 102, and station 0291 sample 101.

     Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes
     /gp804/ctd/ and /bot and included in the MySQL data management tables on
     December 23, 2004.
