Signature of Mesoscale Eddies on Air‐Sea Heat Fluxes in the North Indian Ocean

Abstract

AbstractUsing a combination of 20‐year (1999–2018) remotely‐sensed air‐sea heat flux products and altimeter‐based eddy atlas, we investigate the signature of mesoscale eddies on sea surface temperature (SST) and air‐sea turbulent latent and sensible fluxes, or simply, turbulent heat fluxes (THFs), in the North Indian Ocean. On average, eddy‐induced THF feedback can approach ∼40 W m−2 k−1 for warm‐core anticyclones (AEs) and ∼28 W m−2 k−1 for cold‐core cyclones (CEs) at their extreme values. In addition to these conventional SSH‐SST coherent eddies and their imprints as monopoles in heat fluxes, a comparable proportion of SSH‐SST incoherent eddies (cold‐AEs and warm‐CEs) are surprisingly active in this region, which offset the monopolar paradigm of coherent eddy‐induced THF anomalies or develop a dipole structure when combined with these conventional eddies. In terms of seasonality, the aggregation of SSH‐SST coherent and incoherent eddies in the Arabian Sea develops concentrated monopoles within eddy contours in both summer and winter, with a damped THF located farther away from the eddy core in winter. In the Bay of Bengal, a strong compensation between SSH‐SST coherent and incoherent eddies is observed in summer that leads to null net fluxes, while the winter‐time THF composite of these two eddy types displays a dipolar structure which was described as eddy‐stirring effect in the literature.