Differences in the association of sea surface temperature—precipitating systems over the Bay of Bengal and the Arabian Sea during southwest monsoon season

Abstract

The intriguing, but complex, association among sea surface temperature (SST) and different types of precipitating systems (deep and shallow) over the Bay of Bengal and the Arabian Sea has been elucidated utilizing 16 years of tropical rainfall measuring mission (TRMM) data. The characteristics and their convective forcing of these two seas are fundamentally different due to differences in SST. At a given SST, the occurrence of deeper (shallow) systems is higher (lower) over the Bay of Bengal than in the Arabian Sea. The occurrence of deeper systems increases with SST over both the seas till 30°C and decreases from 30 to 31°C. On the other hand, the occurrence of shallow systems is independent of SST over the Bay of Bengal while it decreases with rise in SST over the Arabian Sea. The prevalence of weaker convective available potential energy and drier mid‐troposphere over the Arabian Sea than over the Bay of Bengal is detrimental for cloud growth and is responsible for lower occurrence of deep systems and higher occurrence of shallow systems. The differences in mid‐tropospheric dynamics and moisture between the Arabian Sea and the Bay of the Bengal play a major role in the occurrence of deep and shallow systems.

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