GP8-02-KA NOAA Ship Ka'imimoana Kwajalein, Marshall Islands - Honolulu, HI November 1-25, 2002 Chief Scientist: Mr. Dave Zimmerman Survey Department: Ens. Sarah Dunsford CTD Personnel: Ens. Sarah Dunsford, Mindy Kelley Final Processing: K. McTaggart ACQUISITION: ST Jason Poe was on leave this cruise. Augmenting ST Randy Ramey was called away at the last minute to a family emergency. Ensign Dunsford volunteered to do CTDs and salinities with the help of the barnacle scientist, Mindy Kelley. Forty-four CTD profiles were collected during this cruise from 8N to 8S along 165E, 8S to 5N along 180, 5N to 8N along 170W, and 9N to 12N along the ship's trackline to Honolulu. The majority of casts were to 1000m, 3 were deep. Cast 0301 was acquired in two pieces, down and up. PMEL's Sea-Bird 9plus CTD s/n 09P3450-0209 measuring pressure (s/n 53586), PMEL's temperature sensors (s/n 1460, 4211) and conductivity conductivity sensors (s/n 197, 354) were used for all casts. The CTD was mounted in the TAO spare custom 24-bottle frame with a new Sea-Bird carousel pylon s/n 407. 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: Only 8 samples were per cast. 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. Laboratory operating temperature was assumed to be between 23-24 degrees Celsius. Raw data were archived on floppy disk and returned to PMEL on CD separate from the data package. The majority of salinities collected along the 165E line were analyzed during the transit from 165E to 180. Rough seas and work on the ship's air conditioning postponed the analysis of the rest of the salinities until the ship reached port in Honolulu. Mindy Kelley ran the salinities in port during the first week of December. 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: GP802S.CAL of secondary sensor data was created at PMEL. Primary data were not used because the residual conductivity scatter between CTD and bottles was greater. Final pressure and temperature calibrations were pre-cruise. A viscous heating correction of -0.0006 C was applied to temperature sensor s/n 1460 but no historical data for a drift correction are available for this sensor (on loan from the PMEL instrument pool). Conductivity fit coefficients were determined using Matlab program CALCOS1. number of points used 245 total number of points 320 % of points used in fit 76.56 fit standard deviation 0.002749 fit bias 0.0011799944 min fit slope 0.99998297 max fit slope 1.0000584 Slope and bias correction values were applied to CTD data and converted directly into netCDF format using CALMSTR and CLB_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. 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. Cast 0231 was missing 0-11 dbar and cast 0321 was missing 0-36 dbar, so their upcasts were used instead of their downcasts. 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). Bad bottle data included cast 0011 sample 2, 0021 sample 12, 0121 sample 10, 0141 sample 1, 0151 sample 6 and 7, 0281 sample 2, 0301 sample 1, and 0361 sample 3. Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes /gp802/ctd/ and included in the MySQL data management tables on December 20, 2002.