Current preliminary version: 2023-04-07 has not been processed by BCO-DMO
CTD data processing typically follows the procedures outlined in Knap et al., 1996 and can be divided into two major stages: (1) CTD signal conversion and dynamic sensor correction, and; (2) static drift corrections and empirical field calibrations. Stage 1 is performed using SeaBird's SEASOFT software and some Matlab scripts, while stage 2 is performed completely in the Matlab environment. The basic steps of stage 1 are: preliminary CTD sensor quality check; determination of the dynamic coefficients associated with time alignment and thermal mass problems; application of pressure filter and velocity filter (0.3 m/s); application of digital filters for erroneous signal removal; and finally average to 2 Hz ready for stage 2 processing. The processing steps in stage 2 include: static drift corrections as determined from the sensor calibration history; empirical field calibration of the conductivity and oxygen sensors; final QC analysis; and bin average downcast data to 2 dbar. Following experience of profiling with the SBE–35RT temperature probes, appropriate routines are being implemented to assess performance of the SBE–03f units against the SBE–35 and implement correction procedures. It should be noted that only downcast data are processed and reported, except for the marker data during bottle fires on the upcast.
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BCO-DMO Processing Notes:
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- merged deployment and recovery information from supplemental info files into the data using the cast_ID
- created the following additional columns: info_filename, filename, cruise_type, cruise_number, cast_number, and cruise_type_text.
- replaced NaN and -999 with the fill value 'nd'.
- combined 'Date deployed' and 'Time CTD deployed GMT' into ISO_datetime_deployed.
- combined 'Date recovered' and 'Time CTD recovered GMT' into ISO_datetime_recovered.
- converted longitude values from degrees West to degrees East (mutliplied by -1).