GP4-03-KA NOAA Ship KA'IMIMOANA Kwajalein, Marshall Islands - Honolulu, HI July 11 - August 7, 2003 Chief Scientist: LCDR Chris Beaverson Survey Department: ST David Fischman CTD Personnel: ST David Fischman Final Processing: K. McTaggart ACQUISITION: Fifty-seven CTD profiles were collected during this cruise. Twenty-three profiles were collected from 8N to 8S along 165E; one test cast at 8S, 170W; and 27 profiles were collected along 180 from 8S to 8N and along the ship's trackline from 8N to 12N. Because the ship was ahead of schedule, 5 extra 1000 m casts were done along the trackline enroute to the Big Eye mooring, at the request of NMFS, as well as one CTD at the Big Eye mooring site. The majority of casts were to 1000m. Five casts were deep (>3000m). Cast 0231 was aborted at 2033m, and cast 0261 was aborted at 386m, owing to a termination failure resulting in loss of communications. PMC's Sea-Bird 9plus CTD s/n 09P13807-0439 measuring pressure (s/n 59788), temperature sensors s/n 4211 (TAO) and s/n 2126 (PMC) and conduc- tivity sensors s/n 303 and s/n 1697 (both PMC) were used for all casts. The CTD was mounted in the TAO spare custom 24-bottle frame with SBE carousel pylon s/n 54. The CTD data stream was passed through 11plus deck unit s/n 376 with factory settings. Digitized data were sent to a Dell personal computer using Windows 98 OS equipped with Sea-Bird'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 Zip disk and CD and the CD was 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, OSI ACI2000 interface, and IAPSO standard seawater batch #P139 dated November, 2000 and #P141 dated June, 2002. Bath temperature was set to 24 degrees Celsius. Raw data were archived on floppy disk and CD and returned to PMEL. No salinity samples were taken for aborted casts 0231, 0241 and 0261. 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: GP403S.CAL of secondary sensor data (te 2126, co 1697) for stations 1-57 was created at PMEL and used to calibrate station profiles 1-57, except station 35. Secondary data for station 35 were noisy owing to a broken pump, so primary data (te 4211, co 303) with pre-cruise calibrations were processed for this cast. Final pressure and temperature calibrations were pre-cruise. A viscous heating correction of -0.0006 C was applied to temperature sensors s/n 2126 and 4211 but no historical data for a drift correction are available for either sensor. Secondary conductivity fit coefficients were determined using Matlab program CALCOS0 for conductivity s/n 1697. An additional offset of -0.004 psu was applied to salinities in order to bring the deep profiles into their historical envelopes. number of points used 538 total number of points 641 % of points used in fit 83.93 fit standard deviation 0.003865 fit bias -0.005309621 min fit slope 1.000248 max fit slope 1.000248 Slope and bias correction values were applied to CTD burst data and converted directly into netCDF format using CALMSTR and CLB_SHIFT_EPS. A dozen bad salinities were flagged: cast 0071 105, cast 0081 104, cast 0101 104, cast 0131 108, cast 0141 102-109-110-111, cast 0151 104, cast 0221 102, cast 0361 104, and cast 0551 101. There are no bottle files in our database for stations 0231, 0241, or 0261. Flagged data are stored in gp403s_eps.clb. 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 7.0. 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. 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_SHIFT_EPS2 applies post-cruise temperature corrections and conductivity calibration coefficients, as well as an offset to salinity, recomputes the derived variables in DERIVE, and converts the ASCII data files to netCDF format. CNV_SHIFT_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 10 db. Because the SBE module LOOPEDIT does not handle package slowdowns and reversals well in the thermocline where gradients are large, CNV_SHIFT_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. Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes /gp403/ctd/ and included in the MySQL data management tables on September 17, 2003.