Arabian Sea mini warm pool during May 2000

Anomalously warmer waters, viz. the Arabian Sea mini warm pool were reported in the southeastern Arabian Sea, which is believed to drive the onset vortex of the southwest monsoon. To understand the characteristics of thismini warm pool, an experiment was conducted on-board INS Sagardhwani during the middle of May 2000. Analysis of the oceanographic data revealed the existence of a mini warm pool with temperature in excess of 30.25°C along 9°N between 68 and 75.5°E during the pre-onset period of the southwest monsoon. This mini warm pool coincided with the regions of low salinity (35.2 PSU) layer and its intensity inversely correlated with the depth of the highly stable (E > 2000 × 10 - 8 m - 1 ) layer. At the core (73.5°E, 9°N) of the mini warm pool, surface temperature was 31.2°C and sea surface salinity was less than 34.6 PSU. This core was found restricted to the upper 5 m water column following the thickness of low-salinity pocket and the resulting increased vertical density stratification. This communication clearly brings out the vertical stability as an important parameter to correlate the intensity of the warm pool. With the occurrence of the southwest monsoon conditions, this mini warm pool dissipated (SST decreased to 30°C). Evidences were obtained for the recirculation of low salinity Bay of Bengal water mass under the influence of a clockwise gyre in the study region.

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