Role of met-oceanic response to the intensification of tropical cyclones: A comparative analysis on cyclone Tauktae and Yaas

Abstract

The present study investigates the physical response of surface met-ocean variables during the tropical cyclones (TCs) Tauktae (14–19 May) and Yaas (23–28 May) along the eastern Arabian Sea and western Bay of Bengal respectively using multi-platform datasets. This study synthesizes scientific understanding of the complex interplay between TCs, Marine heat waves (MHWs), and vertical wind shear; and focuses on their combined effects on ocean dynamics. The TC Tauktae developed and rapidly intensified without encountering any MHW event and required longer lifespan (∼3 days) to reach its peak as an Extremely Severe Cyclonic Storm (ESCS). Conversely, prolonged MHW event, persisting for five-fold duration (26 days), significantly influenced the intensification of TC Yaas into a Very Severe Cyclonic Storm (VSCS) within a shorter duration (∼1.5 days). TC Yaas intensified due to vertical wind shear, which transported heat and moisture from the Arabian Sea, creating favorable environment for its growth and development. Furthermore, the low vertical wind shear preceding Yaas provides favorable conditions for the persistence of MHW events. The presence of an anticyclonic eddy along the track played a crucial role in the intensification of TC Tauktae and Yaas. Before TC Yaas, elevated shortwave radiation and reduced longwave radiation played a significant role in sustaining the MHW event, unlike TC Tauktae. After the landfall of TC Yaas, the barrier layer thickness and mixed layer heat content were still high, whereas these were low in case of Tauktae. This signifies that higher translational speed of TC Yaas, relative to Tauktae, leads to reduced churning effects within the ocean, allowing for the retention of a substantial amount of heat within the mixed layer.