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.