On the Seasonal Variability of Sea Surface Temperature and Air–Sea Fluxes in the Lakshadweep Sea

Abstract

Using satellite-sensed sea surface temperature (SST), winds, and air–sea fluxes, we studied seasonal variability of SST and air–sea fluxes in the Lakshadweep Sea (LS) and quantified their relations. Seasonal variability of SST exhibits a bimodal nature, for that air–sea fluxes and oceanic processes operate differently. Analysis demonstrates that seasonal SST variability due to air–sea fluxes in the LS arises with a time lag of 1 or 2 months. For winter cooling, low solar insolation plays a cardinal role and the effects due to net longwave radiation (NLWR) and latent heat flux (LHF) are surpassed. Although net shortwave radiation (NSWR) is minimum in December, low winter SST with a lag of 1 month occurs in January. All air–sea fluxes are favorable for summer monsoon cooling though cooling is also set by several oceanic processes such as advection, vertical overturning, and turbulent mixing. During pre-monsoon warming months March–April, all air–sea fluxes are favorable. But during intense warming in May, though SST is high (> 29.8 °C) in the LS, air–sea fluxes are not supportive as incoming solar insolation is low and evaporative heat loss is high. This indicates that warming during May is the resultant of the expansion of Indian Ocean warm pool into the LS and westward propagation of the Lakshadweep high (LH) as downwelling Rossby wave. For the post-monsoonal warming during October–November, low NSWR is unfavorable but distributions of LHF and NLWR demonstrate suitable condition. For warming during November, vertical ocean heat convergence and less evaporation act favorably.