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TITLE OF THE DATA SET
Indian Ocean Radiocarbon: Data from the INDIGO 1, 2, and 3 Cruises.
DATA CONTRIBUTORS
H. Gote Ostlund and Charlene Grall
Rosenstiel School of Marine and Atmospheric Science
University of Miami
Miami, Florida 33149
SOURCE AND SCOPE OF THE DATA
The data file included in this subdirectory (NDP036) details C-14
activities from water samples taken at various locations and depths
in the Indian Ocean. Values are presented in the internationally
accepted delta C-14 convention (see, for example, Stuiver and Robinson
1974). The data were collected as part of the INDIGO 1, INDIGO 2,
and INDIGO 3 cruises. The INDIGO 1 cruise collected samples in the
southern Indian Ocean from February 27 through March 26, 1985.
Carbon-14 measurements were made from 74 samples collected at 13
stations located between latitudes 26 degrees S and 48 degrees S. INDIGO 2
began the following year and sampled the northwestern Indian Ocean from
April 1 through April 30, 1986. Carbon-14 measurements were made
from 91 samples at 14 stations located between latitudes 19 degrees S and
9 degrees N. The INDIGO 3 cruise traveled south into the Southern Ocean and
collected samples from January 15 through February 13, 1987.
Carbon-14 measurements were made from 68 samples collected at 7
stations located between latitudes 37 degrees S and 65 degrees S.
These data have been used to estimate the penetration of
anthropogenic CO2 in the Indian Ocean and may be especially
significant because of the inclusion of measurements from locations
in the Southern Ocean near the major point of origin for the deep
waters of the world's oceans. The data file also includes
supporting measurements for potential temperature, salinity,
density (sigma-theta), del C-13, and total CO2.
DATA FORMAT
Four files are provided as DOS ASCII text files in this subdirectory,
including this documentation file (NDP036.TXT), a FORTRAN IV retrieval program
(NDP036.FOR), a SAS input/output routine (NDP036.SAS), and a data file
containing the Indian Ocean radiocarbon data (INDIGO.DAT) from the
INDIGO 1, 2, and 3 cruises.
Table 2 (located in the documentation that describes these
data) presents a partial listing of the data file containing the
Indian Ocean radiocarbon data ((INDIGO.DAT). The data file is
formatted in the following way:
CHARACTER STATION*3, DATE*6, CAST*3, SAMPLER*2
INTEGER BOTTOM, LAT, LONG, DEPTH, POTTEMP, SALINITY,
1 SIGTHETA, TCO2, DC13, DC14
10 READ(2,100,END=99) STATION, DATE, BOTTOM, LAT, LONG, CAST,
1 DEPTH, POTTEMP, SALINITY, SIGTHETA,
2 TCO2, DC13, DC14, SAMPLER
C
100 FORMAT(1X,A3,2X,A6,2X,I4,2X,I5,2X,I4,2X,A3,2X,I4,2X,I5,
1 2X,I5,2X,I5,2X,I4,2X,I5,2X,I7,2X,A2)
where
STATION is the identifying number of the station (data
collection site) (see Ostlund and Grall 1988);
DATE is the date of sampling, presented in a six-digit
format, indicating year, month, and day,
respectively;
BOTTOM is the depth (in meters) of the ocean bottom at the
site of sampling;
LAT is the latitude of the station, presented in degrees
(first two digits) and minutes (last two digits),
with north latitudes represented as positive;
LONG is the longitude (east) of the station, presented in
degrees (first two digits) and minutes (last two
digits);
CAST is the identifying number of the group of four Niskin
sampling bottles simultaneously lowered into the
water;
DEPTH is the depth (in meters) at which the sample was
taken;
POTTEMP is the potential temperature (i.e., temperature
corrected for the effect of adiabatic compression
with increase in depth) given in degrees C * 1000 (see
Pickard and Emery 1982);
SALINITY is the fraction of dissolved salts in sea water,
given in ppt(w/w) * 1000;
SIGTHETA is sigma-theta, the density of seawater at the
given salinity and potential temperature, given as
[density (kg/m**3) - 1000] * 1000;
TCO2 is the total CO2 in umol/kg;
DC13 is del C-13, the deviation in per mil from standard
C-13:C-12 ratio, calculated as del 13 = [(Rsa/Rst)-1] *
1000, where Rsa and Rst are the C-13:C-12 ratios of sample
and standard (obtained from the National Bureau of
Standards), respectively (see Stuiver and Robinson 1974);
DC14 is delta C-14, the deviation in per mil of sample C-14
activity from standard C-14 activity, with correction
for the effects of isotope fractionation, calculated
as delta C-14 = [(Asn/Ao)-1] * 1000, where Asn is the
measured C-14 activity of the sample, corrected for isotope
fractionation, and Ao is the oxalic acid C-14 activity
with the age corrected to 1950 A.D. and the C-13
normalized (see Stuiver and Robinson 1974; Ostlund
and Grall 1988; Stuiver and Polach 1977; Broecker and
Olson 1961); and
SAMPLER is the identifying number of the Niskin bottle from
which an individual sample was collected.
Stated in tabular form, the contents include the following.
_________________________________________________________________________
Variable Variable Starting Ending
Variable type width column column
_________________________________________________________________________
STATION Character A3 2 4
DATE Character A6 7 12
BOTTOM Numeric I4 15 18
LAT Numeric I5 21 25
LONG Numeric I4 28 31
CAST Character A3 34 36
DEPTH Numeric I4 39 42
POTTEMP Numeric I5 45 49
SALINITY Numeric I5 52 56
SIGTHETA Numeric I5 59 63
TCO2 Numeric I4 66 69
DC13 Numeric I5 72 76
DC14 Numeric I7 79 85
SAMPLER Character A2 88 89
_________________________________________________________________________
Missing values for potential temperature, salinity, and sigma-
theta are represented by -9999. Missing values for total CO2 are
represented by -999.
REFERENCES
Broecker, W. S., and E. A. Olson. 1961. Lamont radiocarbon
measurements VIII. Radiocarbon 3:176-204.
Ostlund, H. G., and C. Grall. 1988. INDIGO 1985-1987: Indian
Ocean Radiocarbon. Tritium Laboratory Data Report No. 17.
Tritium Laboratory, Rosenstiel School of Marine and Atmospheric
Science, Miami, Florida.
Pickard, G. L., and W. J. Emery. 1982. Descriptive Physical
Oceanography: An Introduction, 4th ed. Pergamon Press, New
York.
Stuiver, M., and H. A. Polach. 1977. Discussion: Reporting of C-14
data. Radiocarbon 19:355-363.
Stuiver, M., and S. W. Robinson. 1974. University of Washington
GEOSECS North Atlantic carbon-14 results. Earth and Planetary
Science Letters 23:87-90.