Indian Ocean 1995 - Leg 7 Readme

About the Cruise:

From February 1995 through January 1996 the NOAA Ship MALCOLM BALDRIGE
conducted scientific operations on an around-the-world cruise to the
Indian Ocean.  Samples were taken from both the surface water and the
overlying atmosphere to determine carbon dioxide flux across the gas/
water interface.  The ship departed Diego Garcia, UK on August 30, 1995
and arrived in Male, Maldives on October 26, 1995.  Leg 6 was supposed
to end in Colombo, Sir Lanka but political turmoil forced the cruise to
conclude on October 26.  No underway data was collected from the beginning
of this transit since the pump which brings the surface water to the equilibrator
malfunctioned.


Class of Data:  Surface ocean carbon dioxide concentrations

Dataset Identifer:  IO95_Leg7

Statement of how to cite dataset:

     BALDRIGE website: http://www.aoml.noaa.gov/ocd/gcc/baldrige_introduction.php

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


Measurement platform identifier:  IO95_Leg7/NOAA Research Vessel MALCOLM BALDRIGE

Data quality issues:

     Method of Analysis:  Infrared absorption of dried gas.  

     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 (300 ppm, 360 ppm, and 420 ppm) should be considered
     approximate (5 ppm).  While individual data points above 420 or below 300 may
     not be accurate, the general trends should be indicative of the seawater
     chemistry.

     Sampling Cycle:  The system runs on an hourly cycle during which three
     standard gases, three air samples from the bow mast and eight surface water
     samples (from the equilibrator head space) are analyzed on the following
     schedule:

               Minutes after the hour            Sample
                        4                        Low Standard
                        8                        Mid Standard
                       12                        High Standard
                       16                        Water
                       20                        Water
                       25                        Water
                       29                        Water
                       33                        Air
                       37                        Air
                       41                        Air
                       46                        Water
                       50                        Water
                       55                        Water
                       59                        Water



     The two water values are averaged to yield a single hourly value which is merged
     with the air value to determine the air-water difference in fugacity (delta fCO2).
     The time stamp and location are for the top of the hour after the air and two
     water sample analyses. 

     Units:  All xCO2 values are reported in parts per million (ppm) and are for
     dry gas and fCO2 values are reported in microatmospheres (uatm) assuming
     100% humidity at the equilibrator temperature.  Columns have a default value
     of -9 in case of instrument malfunction or erroneous readings.  Furthermore,
     if a questionable xCO2 value, pressure, or temperature value is encountered
     which cannot be readily extrapolated a default value of -9 is placed in
     that field.   


Contact persons for this dataset:

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

     Betty Huss
     (305)361-4395
     Betty.Huss@noaa.gov

Timestamp for dataset reduction:      

Timestamp for most recent update of dataset:  3/16/2006

Time period the dataset refers to:  8/30/1995 - 10/25/1995

Geographic area the dataset refers to:

     Note:  Correction made on 3/16/2006 four days of duplicate data beyond
            the Maldives that are in Leg 8A were deleted from this data set.

     Leg 7 Start:  Diego Garcia, UK (August 30, 1995)
     Leg 7 End:    Male, Maldives (October 25, 1995)
     Leg 7:        Diego Garcia, UK to Male, Maldives

     Chief Scientist(Leg 7):    Rik Wanninkhof, AOML
                              
     System Operators (Leg 7):  Jason Masters, AOML