A mini-warm pool during spring in the Bay of Bengal

Characteristics of the mini-warm pool (MWP) that exists in the Bay of Bengal (BoB) during spring inter-monsoon have been examined. Analysed ocean and atmospheric data revealed warming of ocean water during April, which gradually occupies most of the bay in May, and collapses with the onset of summer monsoon in early June. To define spring MWP, sea surface temperature exceeding 29.5 °C was taken as the criteria. The estimated depth of MWP from model data ranges between 10 – 20 m during April and 15 – 25 m in May, while observations at two moorings suggest that it may increase up to 50 m during spring. It is worth noting that the observed depth of warm water layer (> 29.5 °C) at both moorings is located within the low salinity layer (~ 40 m) showing the importance of salinity for the maintenance of spring MWP. Further, a relationship between the spring MWP and El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events have been noted. However, more studies are required to quantify the effects of ENSO and IOD on spring MWP in the BoB.