The cold pool of the Bay of Bengal and its association with the break phase of the Indian summer monsoon

摘要

During the summer monsoon season, strong coastal upwelling occurs along the southwest coast of India and at the southern tip of India, which cools the surface temperature of the waters around these regions. The summer monsoon current carries the upwelled cold waters into the Bay of Bengal and forms the ‘cold pool of the Bay of Bengal’, with its core south of Sri Lanka and over the south-central Bay of Bengal. The present study focuses on the intrusion of these cold waters into the south of the Bay of Bengal, its interannual variability, and its association with the surface wind during the break phase of the summer monsoon, when strong westerly surface winds flow south of 10°N. The authors hypothesize that the enhanced cooling in the cold pool region during monsoon spells is associated with the strong westerly wind stress there during the break spells of the monsoon. Seven cases of long break monsoon spells that occurred during the nine years from 2001 to 2009 are analyzed, and the results confirm our hypothesis.