CalCOFI 9803SP 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 9803SP was the first El Nino cruise after the full winter
CalCOFI 9802JD.
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 March 1998 cruise, only 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.

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.

Please note that on casts 011 & 012, only the CTD 'Fish' was deployed due to rough
weather. This is our backup 911 CTD deployed with only T, C, & O2 sensors and no
bottles. Cruise-corrected CTD data could be calculated but sta-corrected data are
unavailable since there are no bottle samples.

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:
No obvious operator errors were detected - there were no corrections to line.station or cast
numbers in the .hdr files

Other issues: 
cast 011 & 012 were CTD 'fish' only - something that was tried instead of not deploying the
rosette and getting no data at all. Opting for CTD profiles vs no data.


CalCOFI casts numbers (ie filenames) were changed from 01-16 to 001-016; 980301.* >>> 9803001.*... 

BtlVsCTD averages the primary & secondary temperature. Unfortunately, there is a small
'bug' that miscalculates the average when the secondary temperature is missing.
This bug only affects cruises with a single temperature sensor. BtlVsCTD data flag routine was
used to data code Temp2 as '9' which changes the AveTemp to Temp1 only, fixing the incorrectly
calculate CTD aveTemp.


JRW 05/23/2022


