GP4-06-KA NOAA Ship KA'IMIMOANA Kwajalein, Marshall Islands - Honolulu, HI July 6 - August 1, 2006 Chief Scientist: Linda Stratton Survey Department: ST Karen Taylor CTD Personnel: ST Karen Taylor, Scientist Kris Karnauskas Final Processing: K. McTaggart ACQUISITION: Fifty CTD profiles were collected at 50 stations during this cruise. TWenty-three profiles were collected from 8N to 8S along 165E; 27 profiles were collected from 8S to 8N along 180; and to 12N along the trackline. The majority of casts were to 1000m; 6 casts were deep (>3000m). 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 sensor s/n 524, 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. There was no PAR(V4) sensor for Mike Behrenfeld this cruise. And the oxygen sensor was permanently removed and returned to MBARI after 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. Data overflow and modulo errors occurred on cast 0011 at 1800m on the downcast. The problem was resolved when the system was restarted, logging to cast 0012. The same symptoms and resolution occurred on cast 0311 at 45n on the upcast. Casts 0312 and 0313 contain 45m-0m bottle data. There was also a glitch in the acquisition program during cast 0211 but there was no indication of lost data. Missing and glitchy data were seen in cast 0321. 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. 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. CONDUCTIVITY CALIBRATION: GP406S.CAL of secondary sensor data (te 4211, co 1467) was created at PMEL and used to calibrate all stations 1-50. 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 +0.00038 C. The best results were from an overall fit determined by CALCOS1: number of points used 252 total number of points 298 % of points used in fit 84.56 fit standard deviation 0.002091 fit bias -0.0017251034 min fit slope 1.000036 max fit slope 1.0001004 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_EPS2P3. Version P3 reads files that include 3 optical sensors for OSU (no PAR) carried through as raw voltages. 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_EPS2P3 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_EPS2P3 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. 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_EPS2P3 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. Four bottles were flagged bad: station 21 and 37 sample 105, and station 25 and 29 sample 101. Two bottles were flagged as questionable, both at 200 db: station 18 and 23 sample 105. Final CTD and bottle files were moved to /home/plover/insitu2/DATA/hayes /gp406/ctd/ and /bot and included in the MySQL data management tables on August 16, 2006.