GP2-03-KA NOAA Ship KA'IMIMOANA San Diego, CA - Manzanillo, Mexico March 24 - April 27, 2003 Chief Scientist: Mr. Patrick A'Hearn Survey Department: ST Randy Ramey, ST David Fischman CTD Personnel: ST Randy Ramey, ST David Fischman Final Processing: K. McTaggart ACQUISITION: Sixty-two CTD profiles were collected during this cruise. Twenty-five profiles were collected along the ship's trackline from 12N to 8N and down 110W from 8N to 8S; and 37 profiles were collected along 95W from 8S to 8N and along the ship's trackline from 8N to 12N. The majority of casts were to 1000m. Seven casts were deep (>3000m) and 11 were shallow (<500m). PMC's Sea-Bird 9plus CTD s/n 09P13807-0439 measuring pressure (s/n 59788), temperature sensors (s/n 4211 TAO, 2126 PMC) and conductivity sensors (s/n 1467 TAO, 3438 PMC) were used for all casts. The secondary TC pair were chosen for calibration and processing, however primary TC data were calibrated and processed for casts 0011 and 0021 owing to a faulty secondary temperature cable. The CTD was mounted in the TAO spare custom 24-bottle frame with a new Sea-Bird carousel pylon s/n 88. The CTD data stream was passed through 11plus deck units, 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. Bath temperature was set to 24 degrees Celsius. Raw data were archived on floppy disk and CD and returned to PMEL. The Autosal fan was not plugged in at the start of the first run and so the results for cast 0011 were poor and not used to calibrate the CTD. Autosal readings were erratic and high for cast 0261 samples. The problem was resolved after restandardizing the machine. Cast 0261 samples 1-7 were rerun under the new standard. Autosal run of casts 00321-0341 was not standardized properly. Data were recomputed from uncorrected readings post- cruise. 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: GP203S.CAL of secondary sensor data was created at PMEL. Primary data were not used because the residual conductivity scatter between CTD and bottles displayed an offset as well as a drift over the cruise. Final pressure and temperature calibrations were pre-cruise. A viscous heating correction of -0.0006 C was applied to temperature sensor s/n 2126 but no historical data for a drift correction are available for this sensor because it was borrowed from the MACARTHUR. Secondary conductivity fit coefficients were determined using Matlab program CALCOP0 for conductivity s/n 1697 also borrowed from the MACARTHUR. number of points used 495 total number of points 575 % of points used in fit 86.09 fit standard deviation 0.003227 fit bias 0.0043581923 fit co pressure fudge -5.4964165e-007 min fit slope 0.99983471 max fit slope 0.99983471 Primary conductivity fit coefficients applied to casts 0011 and 0021 were determined using CALCOS1 for conductivity s/n 1467 (new temperature sensor s/n 4211). number of points used 493 total number of points 580 % of points used in fit 85 fit standard deviation 0.003047 fit bias -0.0075281776 min fit slope 1.0003347 max fit slope 1.0005611 Slope and bias correction values were applied to CTD data and converted directly into netCDF format using CALMSTR and CLB_EPS. There was no bottle file for cast 0011 or 0141. Bad salinities were flagged for cast 0111 sample 109, cast 0281 sample 109, and cast 0461 sample 109. Flagged data are stored in gp203s_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 9.0. 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_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. The upcast was used instead of the downcast for cast 0041 because the downcast profile was missing 0-19 dbar. Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes /gp203/ctd/ and included in the MySQL data management tables on May 7, 2003.