Intraseasonal response of mixed layer temperature and salinity in the Bay of Bengal to heat and freshwater flux

Parampil, Sindu Raj and Gera, Anitha and Ravichandran, M and Sengupta, Debasis (2010) Intraseasonal response of mixed layer temperature and salinity in the Bay of Bengal to heat and freshwater flux. In: Journal of Geophysical Research, 115 (C05002). pp. 1-17.

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Abstract

Buoy and satellite data show pronounced subseasonal oscillations of sea surface temperature (SST) in the summertime Bay of Bengal. The SST oscillations are forced mainly by surface heat flux associated with the active break cycle of the south Asian summer monsoon. The input of freshwater (FW) from summer rain and rivers to the bay is large, but not much is known about subseasonal salinity variability. We use 2002-2007 observations from three Argo floats with 5 day repeat cycle to study the subseasonal response of temperature and salinity to surface heat and freshwater flux in the central Bay of Bengal. About 95% of Argo profiles show a shallow halocline, with substantial variability of mixed layer salinity. Estimates of surface heat and freshwater flux are based on daily satellite data sampled along the float trajectory. We find that intraseasonal variability of mixed layer temperature is mainly a response to net surface heat flux minus penetrative radiation during the summer monsoon season. In winter and spring, however, temperature variability appears to be mainly due to lateral advection rather than local heat flux. Variability of mixed layer freshwater content is generally independent of local surface flux (precipitation minus evaporation) in all seasons. There are occasions when intense monsoon rainfall leads to local freshening, but these are rare. Large fluctuations in FW appear to be due to advection, suggesting that freshwater from rivers and rain moves in eddies or filaments.

Item Type:	Journal Article
Publication:	Journal of Geophysical Research
Publisher:	American Geophysical Union
Additional Information:	Copyright of this article belongs to American Geophysical Union.
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	25 May 2010 05:35
Last Modified:	19 Sep 2010 06:07
URI:	http://eprints.iisc.ac.in/id/eprint/28051

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