Variability in abundance and fluxes of dimethyl sulphide in the Indian Ocean |
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Authors: | D M Shenoy M Dileep Kumar |
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Institution: | (1) Chemical Oceanography Division, National Institute of Oceanography, Dona Paula, Goa, 403 004, India;(2) Present address: SAMS, Dunstaffnage Marine Laboratory, Oban, Argyll, PA37 1QA, Scotland, UK |
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Abstract: | Dimethyl sulphide (DMS) is a biogenic gas of climatic significance on which limited information is available from the Indian
Ocean. To fill this gap, we collected data on DMS and total dimethylsulphoniopropionate (DMSPt) by participating in a dozen cruises. Here, we discuss the variability in DMS and DMSPt in the north and central Indian Ocean in terms of their spatial and temporal variation. DMS and DMSPt exhibited significant spatial and temporal variability. Apart from the concentration gradients in DMS within the Arabian
Sea, Bay of Bengal and Central Indian Ocean basins, differences in average abundances were conspicuous between these basins.
The Arabian Sea contained more DMS (mixed layer average was 7.8 nM) followed by the Bay of Bengal (2.8 nM) and the Central
Indian Ocean (2.7 nM). The highest concentrations of DMS and DMSPt (525 nM and 916 nM, respectively) were found in upwelling regimes along the west coast of India during the Southwest monsoon
and fall intermonsoon seasons. Average surface DMS was the highest in the Arabian Sea. On the other hand observed sea-to-air
fluxes of DMS were higher in the Bay of Bengal due to the prevalence of turbulent conditions. In the Arabian Sea wind speeds
were low and hence the sea-to-air fluxes. The total diffusive flux of DMS from the study area to atmosphere is estimated to
be about 1.02 × 1012 g S y−1, which contributes to 4.1–6.3% of the global DMS emission |
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Keywords: | DMS DMSPt Fluxes Indian Ocean Monsoon |
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