README file for S.Atl-91 CTD files. NOAA AOML designation: South Atlantic-91 WOCE/WHP and NODC designation: WOCE AR21, June 1- July, 1991. Contact person: Rik Wanninkhof, Wanninkhof@aoml.noaa.gov CTD data reduction: Doug Wilson, Wilson @aoml.noaa.gov Address NOAA/AOML 4301 Rickenbacker Causeway Miami FL 33149 FILE STRUCTURE: The cast_0xx.cal files, where xx is the cast number, are space delimited text files with the following column headings Pres_dB: pressure (1_dB averaged) T: temperature (_C) Cond: conductivity Sal: salinity (practical salinity scale) o2_V: voltage output of O2 sensor O2_temp: temperature measured by thermistor on O2 probe O2_ml/l: O2 concentration (ml/l) factory calibration The location&time.csv file is a comma-delimited file that contains the time and geographic information for each cast: It has the following column headings Station: XX Cast: OYY DEC_LAT: decimal latitude DEC_LON: decimal longitude YRJD: decimal year and year day in format YYDDD.DD DATE: month/day/year Time (GMT): time when CTD (or hydrocast) was at bottom, hr:min DESCRIPTION: From July 11 to September 2, 1991, the National Oceanic and Atmospheric Administration's (NOAA) Carbon Dioxide (CO2) and Radiatively Important Trace Species (RITS) programs participated in an oceanographic research cruise conducted aboard the NOAA ship MALCOLM BALDRIGE. The appended files with designation, cast_0xx.cal, contain the 1 dB averaged CTD and O2 data from the cruise. The data was obtained primarily in support of the Ocean-Atmosphere Carbon Exchange Study (OACES) and the cruise was not performed to WOCE standards, neither in protocol or sampling density. During Leg 1 of this cruise (Fortaleza, Brazil to Montevideo Uruguay), 33 CTD hydrographic casts and 17 Go-Flo(tm) productivity casts were conducted. Approximately half the CTD cast went down to within 30 m from the bottom, the others were down to about 1000 m. A catastrophic software failure prevented recovery of the CTD data for cast 33. CTD casts were not done on all stations and some stations had several CTD casts. All CTD operations were conducted using the same Neil Brown(tm) Instrument Systems Mark III CTD equipped with standard temperature and conductivity sensors, a Beckman(tm) polarographic dissolved oxygen sensor, and an auxiliary Seabird(tm) temperature sensor. A 24-bottle sampling rosette was used for collecting calibration bottle salinities and chemical tracers. Laboratory calibrations were performed for temperature and conductivity before and after the cruise. The calibrations were used in conjunction with Niskin(tm) bottle data, to calibrate the CTD data. No adjustments or calibrations were performed to the polarographic dissolved oxygen sensor. Pressure and temperature data listed in this report are based on the post-cruise calibration. Temperature accuracy is estimated to be .005讈, and pressure accuracy to be 5 decibars.