  CTD Notes for the RUSALCA 2007 R/V Sever Cruise:
  
  Data collected by Rebecca Woodgate (UW), Tom Weingartner(UAF) and Terry Whitledge (UAF) under grants NSF-ARC-0632154 funding for 
the International Polar Year, and NOAA RUSALCA funding during September, 2007 in the Bering Strait region (including the southern 
Chukchi Sea).  Data were collected from the Russian research vessel R/V Sever as part of a long-term mooring program in the Bering 
Strait.  (http://psc.apl.washington.edu/BeringStrait.html)
  
   Two CTDs were employed on this cruise, a SBE-25 and a SBE-19+. The instruments were strapped and lowered together for all casts.  
Nutrient and Chlorophyll samples were also taken during the cruise, at 2 or 3 depths for each cast.  The contact for these data is 
Terry Whitledge (UAF).  No salinity samples were taken during the cruise.
  
  The T/S data from the SBE-25 (RUSALCA2007_CTD1.dat) looks to be in slightly better condition than the SBE19 (RUSALCA2007_CTD2.dat), 
but the SBE-19 had a payload of ancillary fluorometer, oxygen and PAR sensors, thus both sets of data have been bin averaged (separately) 
and included in the accompanying files.  A number of the oxygen profiles look suspicious (very large difference between the upcast and the 
downcast in conjuction with some non-physical appearing discontinuities). Perhaps the sensor did not get to soak enough at the surface?  
In any case, the oxygen data in particular should be treated with care and caution, plotting the entire .CNV files is recommended.
  
  SeaBird recommended processing procedures were applied to the raw data files to create the 1-decibar binned final data products; the 
processing sequence can be found in the *.cnv files.  Both upcast and downcast processed data can be found in the .CNV files; this data 
is from the step prior to the manual despiking phase.  After the standard SBE Data Processing routines were applied, all upcast and 
downcast profiles were plotted together, and are included in the accompanying ZIP archive.  In these plots, the red trace is the 
downcast and the blue trace is the upcast.   For the SBE-25, a subjective judgment was made to retain the "better" of the upcast/downcast 
pair. For the SBE-19, only downcasts were retained for the final data file.  The data was extrapolated from the uppermost recorded bin to 
the surface (0 db level) and then checked for density inversions.  Generally, density inversions > ~ 0.02 kg/m3??were found only in the 
upper few meters.  We ascribe this to the probable existence of propwash and/or bubbles in the very surface layers.  Linear interpolation 
and constant extrapolation was applied to depth levels with egregious spikes and density inversions.  The data quality flag is set such that 
0 = untouched data, 1 = extrapolated to surface, 2 = interpolated data in the middle of the water column.  The Upcast/Downcast data flag 
indicates whether the upcast (=0) or downcast (=1) was retained.  Some of the CTD data suffers from the typical problems of lowering T/C 
cells through a sharp thermocline.  Fine tuning of the T/C cell sample lags was not performed as the number of casts severely afflicted was 
fairly small. No additional data interpolation or extrapolation was applied to the ancillary sensors.
  
  Final data is included in the following files:
  
  	Header data is stored in the file RUSALCA2007_CTDheader.txt
  	Profile data is stored in the files RUSALCA2007_CTD1.dat and RUSALCA2007_CTD2.dat
 
 
RUSALCA2007_CTD1.dat
SBE-25 Data file columns:
  1. Consecutive Station Number
  2. Pressure (decibars)
  3. Error Flag (0 = untouched; 1 = extrapolated, 2 = interpolated)
  4. Profile Direction (1= downcast; 0 = upcast)
  5. Temperature (deg. C)
  6. Salinity
  7. Density (Sigma-T, kg/m^3)

RUSALCA2007_CTD2.dat
SBE-19+ Data file columns:
  1. Consecutive Station Number
  2. Pressure (decibars)
  3. Error Flag (0 = untouched; 1 = extrapolated, 2 = interpolated)
  4. Profile Direction ( 1= downcast; 0 = upcast)
  5. Temperature (deg. C)
  6. Salinity
  7. Density (Sigma-T, kg/m^3)
  8. Fluorescence (mg/m^3)
  9. Oxygen (ml/l)
  10. PAR (uE/cm^2)
  11. Oxygen Voltage (V)
  12. Fluorescence Voltage (V)
  13. PAR Voltage (V)

See the cruise report for additional details about the CTD stations, online at:
http://psc.apl.washington.edu/HLD/Bstrait/UWmooringreportSEVER2007Aug.pdf

