



     GP4-06-KA
     NOAA Ship KA'IMIMOANA
     Kwajalein, Marshall Islands - Honolulu, HI
     July 6 - August 1, 2006

     Chief Scientist: Linda Stratton
     Survey Department: ST Karen Taylor
     CTD Personnel: ST Karen Taylor, Scientist Kris Karnauskas
     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; 27 profiles
     were collected from 8S to 8N along 180; and to 12N along the trackline.
     The majority of casts were to 1000m; 6 casts were deep (>3000m).

     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 2126 
     and primary cond sensor s/n 524, and secondary temp sensor s/n 4211 and 
     secondary cond sensor s/n 1467.  Also mounted on the A/D channels were a
     transmissometer(V2), fluorometer(V1), and backscatter(V0) sensor for 
     Pete Strutton.  There was no PAR(V4) sensor for Mike Behrenfeld this cruise.
     And the oxygen sensor was permanently removed and returned to MBARI after 
     this cruise.

     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
     V1 deck unit s/n 376 with factory settings.  Digitized data were sent
     to a Dell personal computer using Windows XP OS equipped with SBE's
     SEASOFT Windows acquisition software version 5.30b.  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.

     Data overflow and modulo errors occurred on cast 0011 at 1800m on the
     downcast.  The problem was resolved when the system was restarted, logging 
     to cast 0012.  The same symptoms and resolution occurred on cast 0311 at
     45n on the upcast. Casts 0312 and 0313 contain 45m-0m bottle data.  There 
     was also a glitch in the acquisition program during cast 0211 but there
     was no indication of lost data.  Missing and glitchy data were seen in
     cast 0321.  


     SALINITY SAMPLES:
   
     Salinity analysis was performed using Guildline Autosal 8400B salinometer 
     s/n 61.383, Ocean Scientific ACI2000, and IAPSO standard seawater batch 
     #P145 dated July 2004.  The bath temperature was set to 24 degrees Celsius.
     Eight samples are collected per cast.  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.


     CONDUCTIVITY CALIBRATION:
   
     GP406S.CAL of secondary sensor data (te 4211, co 1467) 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 4211 was +0.00038 C.

     The best results were from an overall fit determined by CALCOS1:

     number of points used   252
     total number of points  298
     % of points used in fit 84.56
     fit standard deviation  0.002091
     fit bias                -0.0017251034
     min fit slope           1.000036
     max fit slope           1.0001004

     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_EPS2P3.  Version P3 reads 
     files that include 3 optical sensors for OSU (no PAR) carried through as 
     raw voltages.


     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_EPS2P3 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_EPS2P3 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.
     Raw voltages for the optical sensors are not copied back but made zeros.
     Because the SBE module LOOPEDIT does not handle package slowdowns and
     reversals well in the thermocline where gradients are large, CNV_EPS2P3
     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 '8888'; when interpolated over greater than 2 db, the
     WOCE quality word is '6666'.  The WOCE quality word consists of a 1-digit
     flag for pressure, temperature (ITS-90), and salinity.

     Four bottles were flagged bad: station 21 and 37 sample 105, and station
     25 and 29 sample 101.  Two bottles were flagged as questionable, both at
     200 db:  station 18 and 23 sample 105.

     Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes
     /gp406/ctd/ and /bot and included in the MySQL data management tables on
     August 16, 2006.
