


     GP9-01-KA
     NOAA Ship Ka'imimoana
     Kwajalein, Marshall Islands - Honolulu, HI
     October 30 - November 25, 2001

     Chief Scientist: Mr. Dave Zimmerman
     Survey Department: AST Amy Frank
     CTD Personnel: AST Amy Frank (CST Sweeney in Honolulu post-cruise)
     Final Processing: K. McTaggart


     ACQUISITION: 

     Fifty-three CTD profiles were collected on this cruise.  Twenty-three
     profiles were collected from 8N to 8S along 165E.  Twenty-four profiles
     were collected from 8S to 8N along 180.  And six profiles was collected
     along the ship's trackline to Hawaii. Four casts were deep (>3500 m),
     and the rest were to 1000 m. 

     PMEL's Sea-Bird 9plus CTD s/n 09P10881-0390 measuring pressure (s/n 
     58950), the ship's temperature sensors (s/n 2027, 2026), and the ship's 
     conductivity sensors (s/n 1537, 1536) were used for all casts (last
     calibrated in March, 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 8mm tape and CD-ROM and 
     returned to PMEL for post-cruise processing.

     Profile data for cast 0381 was not found on any backup.  Neither were
     there bottle salinities for cast 0361.

     CST Sweeney continues to be on medical leave.  Augmenting AST, Amy
     Franks was responsible for running salinities as well as doing CTDs.
     Problems continue with the quality of CTD data during this cruise.
     Casts 0061-0241 were especially bad.  The only troubleshooting done at
     sea was replacing all the interconnect cables by ET Jeff Hill.  
     CTD salinity values were unrecoverable for stations 0071 0-238 db,
     0081 0-149 db, 0091 0-284db, 0101 0-362 db, all of 0151, all of 0181,
     all of 0191, all of 0201, and 0221 0-200 db.

 
     SALINITIES:

     12 samples were taken each cast as usual.  No duplicate samples were taken
     this cruise.  Salinity analysis was performed using Guildline Autosal 8400B
     salinometer s/n 61.383 and 61.667 (no ACI2000 interface).  IAPSO standard
     seawater batch #P136 and #P139 were both used.  Laboratory operating
     temperature ranged between 22-25 degrees Celsius.  There was no sample data
     for cast 0361.

     Salinity analysis was poor.  Bottle salinities tended to be salty of the
     CTD for the entire cruise.


     POST-CRUISE CONDUCTIVITY CALIBRATIONS:

     GP901S.CAL of secondary sensor data (not including any duplicate salts)
     was created post-cruise at the lab.  It's completeness and correctness were 
     scrutinized and ammended where needed.  Primary sensors s/n 1537 and 1467
     were noisier than the secondary sensors 1536 and 2026.  GP901S.CAL was 
     editted to remove records where CTD data were bad or bottle salts were
     hugely bad (delta S>.05).  This reduced the number of records in the .CAL 
     file by 27%.

     Final pressure and temperature calibrations were pre-cruise.  A viscous
     heating correction of -0.0006 C and a historical drift correction of
     zero was applied to temperature sensor s/n 2026.  

     Conductivity fit coefficients were determined using Matlab program
     CALCOS0.  CALCOP programs were not chosen because there were only a few
     deep bottles and the overall poor quality of sample salinity data.  In order
     not to fit the negative scatter in the residuals owing to salty sample
     readings, the standard deviation allowable in the fit was 2.3 instead of 2.8.

                         number of points used   264
                         total number of points  386
                         % of points used in fit 68.39
                         fit standard deviation  0.005005
                         fit bias               -0.016862524
                         min fit slope           1.0004561
                         max fit slope           1.0004561

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

     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 (excluding those flagged as bad).

     NOTE: When the 4 deep profiles were compared to historical profiles, it
     was apparent that the CTD data were too salty.  The offsets were averaged
     and 0.0032 were subtracted from CTD salinities using CNV_SHIFT_EPS and
     CLB_SHIFT_EPS (in order to compute corrected densities for the files).

     Over 27% of burst data were omitted before calibrations, owing to either
     bad CTD burst data or hugely bad bottle salts (delta>.05).  After 
     calibrations, 31 acceptable bottle salts were returned to the .CLB file
     where the problem was only poor CTD data.  Also, seven additional bottle
     salts from deeper depths were flagged as bad and not included in the
     database files.  Eight bottle salts were flagged as questionable.  No
     sample data were provided for cast 0361.

     Final CTD and bottle files were moved to DISK$EPIC1:[HAYES.DATA.GP901.CTD] 
     and included in the MySQL data management tables on January 14, 2002.  Note
     that CTD data files for stations 0071, 0081, 0091, 0101, and 0221 contain
     missing values for salinity where each was truncated.  Note that CTD data
     files for stations 0151, 0181, 0191, and 0201 contain missing values for
     all salinities in the profile.  These 9 files contain good temperature
     values however and are archived on disk HAYES, but they are not available
     to the public through EPIC data selection routines.  
