Role of Environmental Factors in Rapid Intensification and Weakening of Cyclone Ockhi (2017)
• Jyothi Lingala,
• Sudheer Joseph,
• Suneetha P
Jyothi Lingala
Indian National Centre for Ocean Information Services
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Sudheer Joseph
Indian National Centre for Ocean Information Services

Corresponding Author:sjo@incois.gov.in

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Suneetha P
Andhra University,
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## Abstract

In this study, we investigate the oceanic and atmospheric processes that have contributed to the Rapid Intensification (RI) and Rapid Weakening (RW) of Cyclone Ockhi using the HYbrid Coordinate Ocean Model (HYCOM) simulations and Global Forecast System (GFS) outputs. The environmental conditions prevailed before RI showed the presence of thick warm and fresh waters, ample supply of mid-tropospheric relative humidity, and moderate wind shear. The intrusion of dry air, strong vertical wind shear, and unfavourable oceanic conditions annihilated the storm intensity during the RW stage. Compared to the ocean temperature, the vertical structure of salinity showed remarkable differences between the RI and RW locations resulting in contrasting upper-ocean stratification. The dynamic temperature (T$_{dy}$) under the TC core evolved under the influence of upper-ocean stratification showed a large drop at RW compared to RI. T$_{dy}$ provided a better representation of the ocean’s negative feedback on the rapid intensity changes of TC Ockhi compared to TCHP, especially for the region like RI, which was primarily influenced by the salinity stratification. Hence, this study demonstrates the importance of multi-parameter metric like T$_{dy}$ in the assessment of oceanic feedback to TC and its intensity changes.