Research Publications

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Author: search.filters.author.Maneesha, K.Subject: search.filters.subject.Upwelling

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    Biophysical responses to tropical cyclone Hudhud over the Bay of Bengal
    (Taylor & Francis, 2021-07-03) Maneesha, K.; Prasad, D. H.; Patnaik, K. V. K. R. K.
    Cyclone Hudhud originated in the Andaman Sea on 6 October 2014. Later, it intensified into a cyclonic storm on 8 October and eventually made landfall at Visakhapatnam on 12 October as a very severe cyclonic storm. It was intensified off of Visakhapatnam by high stratified waters with a thick barrier layer that held significant heat content. In this study, we analysed the data along the cyclone track using a combination of satellite, in-situ Argo and Bio-Argo data to assess the upper oceanic changes along the Hudhud track. Notable changes were detected in the upper ocean due to its extreme intensification and prior passage through cold-core eddies. A high translation speed and persistent stratification dominated the effects caused by the cold-core eddies on the intensification of the cyclone and the same was attributed to the upwelled subsurface chlorophyll maxima. The biophysical changes in the top 150 m layer derived from Argo floats were in good agreement with the satellite and model data. Further, it was observed that the increase in lightning flash rates also influenced surface productivity during the cyclone. Subsequent to the passage of the cyclone, the ocean took two weeks to achieve its original state.
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    The intrusion of spicy water favours the intensification of Arabian Sea cyclones
    (Taylor & Francis, 2023-03-15) Maneesha, K.; Brahmananda Rao, V.; Patnaik, K. V. K. R. K.; Franchito, S. H.
    The intensity of the cyclones in the Arabian Sea has been increasing in recent years. Approximately ten storms were intensified into severe cyclones over spicy waters of the northern Arabian Sea during 1998-2019. Reduction in upwelling was observed due to decreasing wind speed, which raised the sea surface temperature (SST) and the intrusion of spicy waters from the Red Sea and the Persian Gulf acted as a barrier to mixing in the top layers, especially in May. Consequently, there was a noticeable increase in the heat content of the 50 m surface layer. This research presents two main rationales that explain the intensification of these cyclones. The first rationale explores the increasing trends in SST and ocean internal energy, while the second investigates the influence of the intrusion of spicy Persian Gulf waters into the Oman coast. The results showed that spicy water from the north suppressed the upwelling in the cold core eddy off the Oman coast and that higher SSTs and high latent heat flux almost double the climatological values off the Oman coast in May.