EX0908 Readme


Class of Data:  Surface ocean carbon dioxide concentrations

Dataset Identifier:  EX0908

Expocode: 33KF20090315

Statement of how to cite dataset:

     For information on dataset citation and more, please see Master Readme File.
     Explorer website: http://www.aoml.noaa.gov/ocd/gcc/explorer_introduction.php

Statement of how to cite dataset:

     Explorer website: http://www.aoml.noaa.gov/ocd/gcc/explorer_cruisetracks.php

     For more information on dataset citation please see Master Readme File.


Measurement platform identifier:  EX0908/Explorer

Data quality issues:

     A faulty valve was discovered at the end of the cruise preventing the air
     to be returned to the equilibrator. The air was then pulled out of the equilibrator 
     and just vented out after going through the analyzer. The loss of air was made
     up by ambiant air going through a pre-equilibrator.
     It is not known when the valve went faulty. We estimate the uncertainty on
     the xCO2 values to be around +/- 5 ppm
     All data starting on March 22 was obtained with a reduced EQU flow to try to
     minimize the loss.
     An offset of -3.11 minutes was applied to the SST data (SST was lagging compared to EQU Temp)
     prior to Delta T calculations.
     Water flow problems seem to have occured around JDay 81.25 and 81.3 and the
     xCO2 data shows greater variation so the data has been flagged 3.
     Standard Gases and Reference Gas:  The three standard gases come from CMDL
     in Boulder and are directly traceable to the WMO scale.  The reference gas
     is a non-calibrated gas from a commercial company.  Any value outside the
     range of the standards should be considered approximate (5 ppm).
     While individual data points above 460 or below 300 may
     not be 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              CA02020          458.04           CMDL
           STD3              CA02040          319.82           CMDL                                               
           STD4              CA02030          377.14           CMDL                                               
                                             

     Units:  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.


Contact person for this dataset:  

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

Timestamp for dataset reduction:  3/30/09

Timestamp for most recent update of dataset:  3/30/09

Matlab version used for reduction: 1.04

Time period the dataset refers to:  03/15/2009 - 03/22/2009

Geographic area the dataset refers to:

     Day 1  - Bayonne, New Jersey (40.7 N/74.1 W)
     Day 4  - San Juan, Puerto Rico (18.5 N/66.1 W)
     Day 5  - Charlotte Amalie, St. Thomas (18.3 N/64.9 W)
     Day 6  - Philisburg, St. Maarten (18.0 N/63.0 W)
     Day 7  - Rouseau, Dominica (15.3 N/61.4 W)
     Day 8  - Bridgetown, Barbados (13.1 N/59.6 W)