1. Radiocarbon in the Northern Indian Ocean two decades after GEOSECS.
- Author
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Dutta, Koushik and Bhushan, Ravi
- Subjects
CARBON isotopes ,OCEAN-atmosphere interaction ,MARINE meteorology - Abstract
The
14 C measurements in the Arabian Sea and the Bay of Bengal during the late 1990s offer a way to assess the temporal changes in the inventories of bomb-14 C and its penetration into the ocean, in two decades since GEOSECS expeditions (1977-1978). The mean penetration depth of bomb radiocarbon during GEOSECS (1977-1978) was 270 m, which increased by ∼40% to 381 m in 1994-1998. The small changes in bomb-14 C inventories, significant increase in the mean penetration depths and lowering of the surface Δ14 C values in the northern Indian Ocean indicate the temporal variation of bomb-14 C in two decades is mainly through downward transfer through mixing with deeper waters. The observed bomb-14 C inventory in the northern Indian Ocean agrees with numerical model simulated values, except at the equatorial Indian Ocean. The high bomb-14 C inventory at the equator can be attributed to lateral advection of14 C-enriched waters from the Pacific Ocean through the Indonesian archipelago. The air-sea CO2 exchange rates in the northern Indian Ocean calculated from the bomb-14 C inventories range from ∼7 mol m-2 yr-1 (in the northern Bay of Bengal) to 20 mol m-2 yr-1 (in the equatorial Indian Ocean). Net sea-air flux of CO2 estimated for the northern Indian Ocean between 0° and 25°N is ∼104 ± 30 TgC yr-1 . The Bay of Bengal is a net sink of atmospheric CO2 (∼-1 ± 0.4 TgC yr-1 ), while the Arabian Sea is a source of CO2 (∼69 ± 21 TgC yr-1 ). [ABSTRACT FROM AUTHOR]- Published
- 2012
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