GEOSECS Indian Ocean
              Description of Carbon Data Reprocessing

The original database was obtained from STS/Oceanographic Data Facility,
Scripps Institution of Oceanography, University of California, 
San Diego  A-014, La Jolla, CA 92093. A full documentation of this original
database is given in GEOSECS7.DOC.

There are two ascii data files containing reanalyzed GEOSECS data.
GEOSECS1.CSV which is a comma-delimited file containing Indian Ocean
Niskin bottle data and GEOSECS2.CSV which is a comma-delimited file containing
Indian Ocean large volume Gerard barrel data. The following list of parameters and the corresponding unit of measurement was selected for the purpose of studying carbon cycle in the ocean.  Please note, the unit of these parameters
remains the same as the original database.

             INDIAN OCEAN NISKIN BOTTLE DATA

                 FIELD                         UNIT
    1. STA       station number                integer
    2. BOT       bottle number                 integer
    3. LAT       latitude                      degree
    4. LON       longitude                     degree
    5. DATE      sampling date                 MoDaYr
    6. PRES      pressure                      dbar
    7. DEP       depth                         meters
    8. TEMP      temperature                   deg C
    9. SAL       salinity                      pss
   10. O2        oxygen                        umol/kg
   11. TALK      total alkalinity              umol/kg
   12. TCO2      total CO2                     umol/kg
   13. PO4       phosphate                     umol/kg
   14. SIO3      silicate                      umol/kg
   15. NO2       nitrite                       umol/kg
   16. NO3       nitrate                       umol/kg
   17. THETA     potential temperature         deg C
   18. SIGMA0    density referenced to
                 sea surface
   19. AOU       apparent oxygen utilization   umol/kg
   20. DELC13    delta C13                     permil
   21. TRITIUM                                 H3 (TU)

       INDIAN OCEAN LARGE VOLUME GERARD BARREL DATA

                 FIELD                         UNIT
    1. STA       station number                integer
    2. BOT       bottle number                 integer
    3. LAT       latitude                      degree
    4. LON       longitude                     degree
    5. DATE      sampling date                 MoDaYr
    6. PRES      pressure                      dbar
    7. DEP       depth                         meters
    8. TEMP      temperature                   deg C
    9. SAL       salinity                      pss
   10. O2        oxygen                        umol/kg
   11. TALK      total alkalinity              umol/kg
   12. TCO2      total CO2                     umol/kg
   13. PO4       phosphate                     umol/kg
   14. SIO3      silicate                      umol/kg
   15. NO2       nitrite                       umol/kg
   16. NO3       nitrate                       umol/kg
   17. THETA     potential temperature         deg C
   18. SIGMA0    density referenced to
                 sea surface
   19. AOU       apparent oxygen utilization   umol/kg
   20. DELC14W   delta C14 (Univ. of Wash.)    permil
   21. DELC14M   delta C14 (Univ. Of Miami)    permil

To determine if the original database is consistent in quality with
data obtained in recent years, comparisons of data obtained in water
samples deeper than 2000 m between GEOSECS (1978) and DOE/WOCE (1995),
and between GEOSECS and NOAA/OACES (1995) are made. The comparison is
made only for GEOSECS stations where re-occupation was made within one
degree of the station location in recent cruises. The assumption is made
that deep water properties in these crossover stations should remain
the same even though measurements were made about two decades apart
because water masses at these depth are free of anthropogenic and other
short term effects. Results of such comparison indicate that hydrographic
properties , such as temperature, salinity, and oxygen concentration, are
highly consistent between old and new data sets. Total alkalinity (TALK)
shows some degree of scatter, but the overall average of the difference
between old and new data sets is 0.8 +/- 6.0 umol/kg, which is within
the precision of the GEOSECS TALK measurements. Thus, there is no need
to make adjustment of GEOSECS TALK data in the Indian Ocean. However,
the TCO2 values in GEOSECS database are consistently and systematically
higher than those observed in DOE/WOCE and NOAA/OACES data sets. Using
multi-parameter least squares linear regression method, the difference
of TCO2 in these crossover stations is determined.  The mean difference
between GEOSECS and recent high precision measurements for these deep
waters is determined to be 21.6 umol/kg, with a standard deviation of
4.1 umol/kg. Hence, the original data set has been corrected for this
difference in TCO2 for the whole water column.  The data set presented here
represents the corrected TCO2 alone. The quality of temperature, salinity,
and oxygen concentration has been checked to be acceptable, and hence no
corrections are needed for these parameters. None of other parameters in the
list were checked, and are assumed to be equally good. Hence no corrections
are applied to the rest of parameters in the list.