



     GP2-06-KA
     NOAA Ship KA'IMIMOANA
     San Diego, CA - Manzanillo, Mexico
     March 30 - April 29, 2006

     Chief Scientist: Andy Shepherd
     Survey Department: ST Karen Taylor
     CTD Personnel: ST Karen Taylor, Scientist Majo Boluarte-Baca
     Final Processing: K. McTaggart


     ACQUISITION: 

     Twenty-nine CTD profiles were collected at 29 stations during this cruise.
     Sixteen profiles were collected from 8N to 7S along 110W.  Thirteen profiles
     were collected from 5S to 8N along 95W.  The majority of casts were to 1000m.
     Four casts were deep (>3000m) 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 2126 
     and primary cond sensors s/n 1697, 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; and a dissolved oxygen(V6) sensor for Majo.  There was no
     PAR(V4) sensor for Mike Behrenfeld 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.

     Another 155m of cable was cut off owing to broken strands this cruise (500m
     was cut off during GP106) and the cable was reterminated twice.  Approxi-
     mately 6300m of cable remains.  Modulo errors are intermittent, increasing 
     in number after the last retermination from 8 to 27 on the last cast.  I'll 
     recommend that another 400m be cut off (totaling 1050m) before GP306.  The 
     cable was lubed (presumably by roller brush) coming in from the last deep 
     cast at station 29 (3000m).


     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.  There were no higher latitude 
     or half-degree stations owing to a medevac to the Galapagos and mooring
     operations.  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.


     OXYGEN SAMPLES/CALIBRATION:

     No oxygen samples were taken and so the oxygen sensor data have only 
     pre-cruise Sea-Bird calibrations applied (dated 29-Dec-2005).
    

     CONDUCTIVITY CALIBRATION:
   
     GP206S.CAL of secondary sensor data (te 4211, co 1467) was created at PMEL  
     and used to calibrate all stations 1-29.

     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 +0.00030 C.

     The best results were from an overall fit determined by CALCOS2, slightly
     better with historical profiles than CALCOS1:

     number of points used   179
     total number of points  227
     % of points used in fit 78.85
     fit standard deviation  0.00216
     fit bias                0.00047916766
     min fit slope           0.99990047
     max fit slope           0.99996362

     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_EPS2PO (version PO reads 
     files that include optical data for OSU carried through as raw voltages
     and MBARI oxygen data in ml/l and umol/kg).


     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_EPS2PO 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_EPS2PO 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.
     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_EPS2PO
     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.

     Two profiles had to be replaced by their upcasts: 0071 and 0291.  Cast
     0291 could have been editted by hand for bad data between 2796-2850 dbars.
     Program get_upcast.f was used to reverse the records in the .cnv files.

     Seven bottles were flagged bad: station 9 samples 105, station 11
     samples 101, 105, 110, station 13 sample 104, station 26 sample 105, 
     and station 28 sample 105.

     Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes
     /gp206/ctd/ and /bot and included in the MySQL data management tables on
     May 5, 2006.
