CalCOFI 9904JD CTD Data Processing Notes

This cruise's CTD sensor data look very clean. No sensor issues were identified
visually. There were some changes in fluorometer sensitivity that required separate
plotting & regression to estimate chl-a from flV. Note that BtlVsCTD dynamically
regresses each cast's sensor data versus bottle. So the cruise-average sensor vs 
bottle regression corrections are primarily for stations without bottle samples.
This is common on Winter & Spring cruises where the pattern is extended north and
fewer or no bottle samples are taken. It was common practice pre-2000 to not process
or report northern station data since those stations were not occupied each quarter.
This was changed later so newer Winter & Spring IEH & CTD data include northern 
stations.
Seabird 911+ configuration: dual T, C, pumped; Beckman/YSI O2 sensor; Datasonics/Benthos Altimeter;
Biospherical PAR & surface PAR; Transmissometer (although M & B were not calculated from deck test
data, so BAC & %Trans values are not calibrated).
Fluorometer sensitivity were determined by regression since no notes or console ops were
available.
Cast 001-003, 024-025, 064-065 are labeled V0C in the regression spreadsheet
Cast 004-023, 026-028, 035-063, 066 are labeled as V0A in the spreadsheet
Cast 029-034 are labeled V0B in the spreadsheet
There casts were bottle corrected dynamically AND using different cruise-ave bottle correction
coefficients (Cruise-ave Est Chla). Because of the changes in fluorometer voltage sensitivity,
casts were run in multiple bins. This generated multiple metadata files which were merged.

The O2 sensor vs bottle data look excellent so I assume it was calibrated right before the
cruise. Typically near-surface data have more scatter but this cruise's regression is one of
the tightest I've every plotted for the Beckman/YSI O2 sensor.

Cast 001 line.sta in .hdr changed from 93.26.7 to 93.3 26.7
Cast 050 line.sta in .hdr changed from 83.40.6 to 83.3 40.6

Because of the changes

JRW 08/07/2021
