CalCOFI 9712SP CTD Date Processing Notes

Number of station-casts: 9 El Nino CalCOFI Station on Line 90

Summary: 1998 wwould be an El Nino year so CalCOFI planned to sent the team to 
collect hydrographic data each month. In addition to the full quarterly cruises, 
abbreviated cruises will sample Lines 90 & 80. The RV Robert Gordan Sproul was 
commissioned for these short cruises. CalCOFI 9712SP was a feasibility test cruise
to test the setup & capabilities of the Sproul & gear. 
The CTD was deployed off the fantail using the rear A-frame.
Not ideal since the ship's prop wash would 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 December 1997 cruise, only 9 stations on Line 90 were occupied. Other
El Nino cruises on the Sproul would schedule 20 stations.
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.

These data are dedicated to the intrepid, dedicated technicians who sail every
month, under 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. 
The single set of primary sensors: temp, cond, & O2 worked well this 
cruise and no replacements were required. T & C sensors were on their first cruise since
being serviced & calibrated. Since the cruises were monthly, there was no time to send
the sensors in for calibration. The same set of sensors were used for multiple cruises.
The O2 sensor was calibrated in Oct 1997 along with the T & C sensors. The O2 sensor worked
well near-surface even with prop wash. Near-surface O2 sensor data agree very well with
bottle samples. The 0.999 Rsquare in the bottle O2 vs sensor O2 data supports 
this statistically. But remember there are fewer bottle samples to compare to sensor data
this cruise.

Software: DOS Datcnv(Seasoft exe), running in a Windows XP virtual machine on Windows 7.
Additional Seasoft processing done using v7.23.2 SBE Data Processing. Since the no sensors were
changed, only one .xmlcon file was used in the Derive module. 

Corrections:
Cast 001 had to be run separately since SPAR was erroneously added to the con. This was
corrected on Cast 002-009.
Cast 003 & 004: CalCOFI cruise number was reported as SP9712 in the .hdr file. This
was corrected to 9712.
Cast 009: Cast number was corrected to '009' from '971208'.

Other issues: 
cast 003 & 004 had pressure spikes that had to be removed from the unsplit .cnv in order
to get downcast and upcast .cnvs to binavg.

Cast 003 had to be run separately in BtlVsCTD Step 2, which generates the station data .csvs.
Reason unknown.

All surface depths in the IEH file were changed from '1' to '2' so the surface data would 
append the surface CTD 2m data.

CalCOFI casts numbers (ie filenames) were changed from 01-09 to 001-009; 971201.* >>> 9712001.*... 

BtlVsCTD averages the primary & secondary temperature. Unfortunately, there is a small
'bug' that miscalculates the average when the secondary temperature is missing. I could
fix this but data processing is finished. Plus it only affects cruises with a single 
temperature sensor.
Now that all the cruises have been processed. It's time to build a CTD database. 
There may be interest in processing the pre-9308 test cruises but they will not
be critical to the database, perhaps added later. I would like to process and include
the monthly cruises during 1998 El Nino. So these cruises will be processed next, as 
time permits.

JRW 05/23/2022


