Arabian Sea mini warm pool and the monsoon onset vortex

Warm pools – regions with sea surface temperature (SST) in excess of 28°C – in the ocean occupy a special place in tropical climate owing to their impact on tropical convection. The southeastern Arabian Sea presents SST in excess of 30°C for two to three months preceding the onset of the summer (southwest) monsoon over India. Recently, several attempts have been made to understand the processes that cause such high SSTs in the region. The literature is also strewn with observations and modelling of a ‘monsoon onset vortex’ forming over the warm pool. This paper is a review of our current understanding of the Arabian Sea mini warm pool and its possible role in the formation of the monsoon onset vortex.