GU0805-Leg 2 Readme

Class of Data:  Surface ocean carbon dioxide concentrations

Dataset Identifer:  GU0805 Leg 2

Expocode:  33GG20081028

Statement of how to cite dataset:

     Gordon Gunter website: http://www.aoml.noaa.gov/ocd/gcc/rvgunter_introduction.php

     For more information on dataset citation and for a full description of the  
     instrumentation and procedures, see the Master Readme file accessible
     thru the Master Readme link located in the left navigation bar of the
     R/V Gordon Gunter web pages.
 
Measurement platform identifier:  R/V Gordon Gunter

Data quality issues:

     The data reduction for this dataset was done using the Matlab Reduction
     Program version 1.03.

     Standard Gases and Reference Gas:  The three standard gases come from Scott-Marrin, Inc.,
     and are calibrated with primary standards that are directly traceable to the WMO scale.  
     The zero gas is a non-calibrated ultra-high purity gas from a commercial company.  Any 
     value outside the range of the standards should be considered approximate (5 ppm).
     While individual data points above 450 or below 245 may be less accurate, the general 
     trends should be indicative of the seawater chemistry.  
     The standards used on the cruise are:

           STANDARD          TANK #       CONCENTRATION       VENDOR
           STD1                               0.00         Commercial
           STD2              ja 2280          248.73       Scott-Marrin, Inc.
           STD3              ja 2292          372.88       Scott-Marrin, Inc.  
           STD4                               450.59       Scott-Marrin, Inc.                 

                                       

     Std1 (0 ppm) ran out of gas and Std4 (highest std) pressure regulator failed,
     which means that the LICOR was neither zeroed nor spanned. Consequently the
     remaining standards were quite a bit off (about 50 and 80 ppm) from their
     certified values at the beginning and they remained that way. This introduces
     a little more uncertainty in the final data as the linearity of the LICOR
     response when it is out of calibration is questionable.

     Also, as a consequence, the measured xCO2 values were corrected using only
     the 2 remaining standards (~370 and 450 ppm). Using the Matlab program v1.03,
     this flagged ALL the data with flag 3 because less than 3 standards were used. 
     Finally, because most of the seawater xCO2 values were less than 370 ppm,
     most of the data has been flagged as Out of Std Range.
                                             
     All xCO2 values are reported in parts per million (ppm) and fCO2
     values are reported in microatmospheres (uatm) assuming 100% humidity
     at the equilibrator temperature.

Ship Information:

     NOAA Research Vessel Gordon Gunter website:  http://www.moc.noaa.gov/gu/index.html

Scientists responsible for technical quality of this dataset:

     Rik Wanninkhof
     (305)361-4379
     Rik.Wanninkhof@noaa.gov 

     Denis Pierrot
     (305)361-4441
     Denis.Pierrot@noaa.gov

Timestamp for dataset reduction:  2/13/09

Timestamp for most recent update of dataset:  3/31/09

Time period the dataset refers to:  10/29/2008 - 11/12/2008

Geographic area the dataset refers to:

     Gulf of Mexico