HB1105 ReadMe

Class of Data:  Surface ocean carbon dioxide concentrations

Dataset Identifier:  HB1105-Legs 1-5 Autumn Bottom Trawl Survey

Expocode: 33HH20110909

Statement of how to cite dataset:

     Bigelow website: http://www.aoml.noaa.gov/ocd/gcc/rvbigelow_introduction.php
     For more information on dataset citation please see Master Readme File.

Measurement platform identifier:  NOAA Ship Henry B. Bigelow, R225

Time period the dataset refers to:  9 Sept, 2011 - 15 Nov, 2011

Geographic area the dataset refers to:

      Latitude,  34.4 to 44.7 degree north
      Longitude,  65.7 to 76.0 degree west

Standard and Reference Gases:  
     The four CO2 standard cylinders come from Scott-Marrin, Inc., and are 
     calibrated with primary standards that are directly traceable to the 
     WMO scale.  The zero gas is ultra-high purity air.  Any value outside
     the range of the standards should be considered approximate (+/-5 ppm).
     While individual data points above 520 or below 200 may less accurate,
     the general trends would be indicative of the seawater chemistry.  
     The standards used on the cruise are:

      STANDARD        TANK #        [CO2]ppm       VENDOR
         STD1         JA02645        204.74      Scott-Marrin
         STD2         JA02273        317.49      Scott-Marrin
         STD3         JA02285        372.23      Scott-Marrin
         STD4         JA02647        518.24      Scott-Marrin
         STD5         JA03093          0.00      Scott-Marrin

Data quality issues:

     The LICOR analyzer was serviced on 8 October, between legs 2 and 3 of HB1105.
     To ensure consistancy, the data for legs 1 and 2 were processed together and 
     the data for legs 3 through 5 were processed together.

     The files containing the 15-second averages of the ship's underway sensors were
     used to fill gaps in the data appended to the CO2 data in real-time (new values: 
     3273 barometric pressures, 3104 sea surface temperatures, 3081 salinities).

     After the merging of CO2 data with the data files of ship's sensors, there 
     remained three gaps of more than ten analyses without important supporting data.
     From 15:04 to 15:27 on 27 Sept and from 14:23 to 14:48 on 28 Sept, the missing 
     data were barometric pressure, SST, and salinity.  A value of 32 psu was 
     assigned as the salinity.  From 04:36 to 05:58 on 28 Sept, SST and salinity were 
     missing.  A value of 33 psu was assigned as the salinity.  

     For the fifty analyses before and after each relavant gap, the average difference 
     between the LICOR and barometric pressures was 0.12 (+/- 0.18) mbar and the 
     average difference between the equilibrator temperature and SST was 0.25 (+/- 0.24) 
     degree centrigrade.  For these gaps, the barometric pressure was estimated by 
     adding 0.12 to the LICOR pressure and the SST was estimated by subtracting 0.25 
     from the equlibrator temperature.


Timestamp for dataset reduction:  22 Nov, 2011

Timestamp for most recent update of dataset:  22 Nov, 2011

Matlab version used for reduction: 1.10

Contact person for this dataset:  

     Kevin Sullivan
     (305)361-4382
     Kevin.Sullivan@noaa.gov