CalCOFI 9812SP CTD Date Processing Notes

Number of station-casts: 16 El Nino CalCOFI Station on Line 90 & 80

Summary: 1998 was an El Nino year so CalCOFI sent the team to collect hydrographic 
data each month. In addition to the full quarterly cruises, abbreviated cruises 
sampled Lines 90 & 80. The RV Robert Gordan Sproul was commissioned for these 
short cruises. 
CalCOFI 9812SP was the last monthly El Nino cruise in 1998 - a busy busy year.
The CTD was deployed off the fantail using the rear A-frame.
Not ideal since the ship's prop wash can mix the surface layer but there was no
sideboard A or J frame. A davit was installed on the port rail to deploy the nets.
On this Dec 1998 cruise, 16 stations of the scheduled 20 stations were occupied.
The Sproul is not a very good open ocean vessel because the rear deck is only a
~1.5m above the water. Sampling was done on the fantail under the A-Frame.
Any weather makes it very difficult to deploy the gear and sample.

These data are dedicated to the intrepid, dedicated technicians who sail every
month, in sometimes VERY rough conditions, on the Sproul, a round-hulled river/bay
boat. 1998 was a very busy year and it tested everyone's sea-legs & dedication.

The basic Seabird 911 CTD with 20 bottles was deployed to 515m, depth-permitting,
following the usual CalCOFI protocols. Lowering to 10m for 2mins then returning to
surface before starting data acquisition. Then lowering at 20-30m/min for the first
100m then 40-50m/min to terminal depth. This winch setup could rarely reach 60m/min
and with the ship pitching a lot. The CTD was lowered at a speed that would keep
adequate tension on the conductive wire. 
Deploying a secondary set of temperature and conductivity sensor is standard after we
lost some salinity data due to a faulty conductivity sensor earlier this year. 
The primary set of sensors: temp, cond, & O2 worked well this cruise with no replacements. 
The secondary set of T & C sensors also worked fine. All sensors were serviced in Aug 1998, 
before CalCOFI 9809NH.
The O2 sensor agreed really well with botle samples even near-surface with prop wash. 
The overall Rsquare was 0.999 regressing bottle O2 vs sensor O2 data. 
Please remember there are fewer bottle samples to compare to and correct
the sensor data these shorter cruises.
No nutrients samples were taken on these ancillary CalCOFI Sproul cruises due to lack of lab
space & nutrient personnel.
 
Software: Seabird SBE Data Processing modules are able to use the .con files from the cruise. 
So running the DOS Datcnv(Seasoft exe) in a Windows XP virtual machine 
on Windows 7 was not necessary. All processing was done using SBE Data Processing v7.23.2.

Corrections:
Cast 016 line.station number was corrected in the .hdr file from 83.40.642 to 83.3 40.6.

Other issues: 
No obvious or noted problems this cruise

CalCOFI casts numbers (ie filenames) were changed from 01-20 to 001-020; 981201.* >>> 9812001.*... 


JRW 06/05/2022


