Significant Role of Ocean Heat Content on the Cyclone Intensity Over the North Indian Ocean

Recent evidence shows that the subsurface ocean structure plays an important role in modulating air-sea fluxes during the storm, which affects the change in intensity. We investigated the importance of surface sea temperature (SST) and the heat content of the upper ocean (UOHC) in the intensification of the tropical cyclone (TC). From an oceanic environmental viewpoint, a rapid deepening of TC central pressure occurs when UOHC is relatively high on a basin scale, while composite distributions of UOHC, vertical wind shear, lower tropospheric relative humidity, and wind speed occurring in cases of rapid intensification are different for each TC season. To explore the influence of UOHC on TC intensification, analyses using MW-IR-OISST, SLA, and Geostrophic Currents data for the cases of Cyclones namely Kyarr (2019), Sidr (2007), Ockhi (2017), Mukda (2006), Nanauk (2014). The increase in Ocean heat content anomaly (OHCA) led to the intensification of these five cyclones even though there are cold-core eddies along their tracks and also suppression of intensity is caused by a decrease in Ocean Heat Content Anomalies. These results suggest that UOHC plays an important role in TC intensity and its intensification. This analysis confirms that consideration of the underlying eddies in the cyclone tracks, UOHC variations must be considered in forecasting the cyclone intensity and its track.

Keywords: Ocean heat content, Sea level anomaly, Sea surface temperature, ACE.