This database presents the
results of the surface water
and atmospheric underway
measurements of mole
fraction of carbon dioxide
(xCO2), sea surface
salinity, and sea surface
temperature, obtained
during the World Ocean
Circulation Experiment
(WOCE) Indian Ocean
survey cruises (December
1994-January 1996).
Discrete and underway
carbon measurements were
made by members of the
CO2 survey team. The
survey team is a part of the
U.S. Joint Global Ocean Flux
Study supported by the
U.S. Department of Energy
to make carbon-related
measurements on the
WOCE global survey
cruises.
Approximately 200,000 surface seawater and 50,000 marine air xCO2 measurements were recorded. Seawater values ranged from 310 ppm to greater than 610 ppm. The lowest values (~50 ppm below atmospheric) were measured in the southwestern Indian Ocean, south of Madagascar. The highest values (more than 250 ppm higher than atmospheric) were found in the Arabian Sea associated with the southwest monsoon upwelling.
All measurements were made using the new fully automated system, designed by the scientists of the Princeton University Ocean Tracers Laboratory. This system was continuously running during all nine Indian Ocean cruises aboard the Research Vessel Knorr. The system had a response time of ~1 min and a long-term precision and accuracy of ~0.4 and 1 ppm, respectively. The equilibrator design is a modification of a counterflow disk stripper that has been used in the past to extract soluble gases from seawater. The detector is a dual-beam infrared spectrometer. Calibration and operation of the instrument as well as data logging are computer controlled and require minimal attention. The design is such that other instrumentation can be easily added. Details of the instrument control, calibration, and efficiency tests for this instrument are given to assist others interested in building similar-type systems.
