GP1-04-KA NOAA Ship KA'IMIMOANA San Diego, CA - Manzanillo, Mexico March 26 - April 22, 2004 Chief Scientist: Dave Zimmerman Survey Department: ST Randy Ramey, ST Shawn Gendron CTD Personnel: ST Randy Ramey, ST Shawn Gendron Final Processing: K. McTaggart ACQUISITION: Forty-seven CTD profiles were collected during this cruise. Twenty-one profiles were collected from 8N to 8S along 110W. Twenty-six profiles were collected from 8S to 8N along 95W, and along the ship's trackline to 12N. The majority of casts were to 1000m. Seven casts were deep (>3000m) and one was to 500m (a test cast for the CTD). PMC's Sea-Bird 9plus CTD s/n 09P13807-0439 measuring pressure (s/n 59788), temperature sensors s/n 1710 (TAO) and s/n 4211 (PMC) and conduc- tivity sensors s/n 1697 (PMC) and s/n 1467 (TAO) were used for all casts. The CTD was mounted in the TAO spare custom 24-bottle frame with TAO SBE carousel pylon s/n 407. The CTD data stream was passed through TAO 11plus deck unit s/n 376 with factory settings. Digitized data were sent to a new Dell personal computer using Windows XP 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 a Sony thumb drive and DVD. DVDs were 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 and 61.383, OSI ACI2000, and IAPSO standard seawater batch #P141 dated June 2002 and #P143 dated February 2003. Bath temperatures were set to 24 degrees Celsius. From now on, only 8 samples will be collected per cast instead of 12, and no samples will be collected from the half-degree stations between 3N-3S. Raw data were archived on DVD along with CTD data. Intermittent problems were resolved when the Autosals were plugged into clean power instead of utility power. New heater lamps were installed in Autosal 61.383. 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. Two runs could not be used in calibrating the CTD owing to bad standardizations; stations 0071-0131 and 0201-0211 have no bottle data. POST-CRUISE CONDUCTIVITY CALIBRATIONS: GP104s.cal of primary sensor data (te 1710, co 1697) was created at PMEL and used to calibrate all stations 1-47. Final pressure and temperature calibrations were pre-cruise. A viscous heating correction of -0.0006 C was applied to temperature sensor s/n 1710 but no historical data for a drift correction are available. For conductivity 1697, stations 1-47, CALCOS0 was used to determine the fit: [sta,slope,bias,newbotco,newctdco]=calcos0(stat,cond,pres,botc,2.8,1,47); number of points used 181 total number of points 213 % of points used in fit 84.98 fit standard deviation 0.003135 fit bias 0.0019262176 min fit slope 0.99984963 max fit slope 0.99984963 Slope and bias correction values were applied to CTD burst 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 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_EPS1 applies post-cruise secondary 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_EPS1 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. Because the SBE module LOOPEDIT does not handle package slowdowns and reversals well in the thermocline where gradients are large, CNV_EPS1 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. Compared to historical deep casts, GP104 deep casts were on the salty edge of the historical envelope. No salinity offsets were applied. Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes /gp104/ctd/ and /bot and included in the MySQL data management tables on May 5, 2004.