On the understanding of very severe cyclone storm Ockhi with the WRF-ARW model

Abstract

Understanding the dynamics of tropical cyclones (TC) in terms of intensity, and their trajectory is essential for adequate early warning and mitigation. The present study attempts to understand the synoptic features of the recent TC Ockhi through a simulation-based approach with the Weather Research and Forecasting (WRF, version 3.8.1) model. Ockhi is considered as a unique TC that originated from depression in the Bay of Bengal on 29 Nov 2017, recurved towards the Arabian Sea, where it intensified into a very severe cyclone storm and weakened on 5 Dec 2017. WRF model forced with initial condition from (Global Forecasting System) GFS data and Sea Surface Temperature (SST) from Group for High-Resolution SST (GHRSST) product for different lead times to test the potential sensitivity of the model. One with an extended period from 20 Nov to 20 Dec. 2017 and another initiated from 27 Nov to 6 Dec 2017. Comparison of the simulated track with the best track estimates from the Indian Meteorological Department (IMD) indicated an overall track deviation greater than 100Km for both the simulations. The analysis with the extended lead time simulation indicates that the WRF simulated sea level pressure (SLP) and wind intensity are close to that observed by Arabian sea buoys; CB02, AD08, AD10, and AD07. Daily averaged wind estimate comparison of WRF1 with Scatsat-1 and ERA-5 indicates that the model is slightly overestimating, whereas comparison of peak wind intensity with the time instantaneous swath product of Scatsat-1 leads to underestimation. Analysis of various simulated synoptic features of the cyclone, as discussed in this paper, indicates that the model is skillful in capturing the various stages of cyclone Ockhi.

Climate, trends and variability of extreme winds along the southwest coast of India

“…This includes the extremely severe cyclonic storms (ESCS) Tauktae (14–19 May 2021) and Maha (30 October–7 November 2019), and the very severe cyclonic storms (VSCS) Vardah (6–13 December 2016), Ockhi (29 November–6 December 2017) and Vayu (10–17 June 2019) (Figure 4). The VSCS Ockhi developed on 29 November 2017 has passed through the southern tip of Kerala and resulted in the loss of life and severe damage to the properties (Mukherjee & Ramakrishnan, 2022; Sanap et al, 2020).…”

“…According to Indian 4). The VSCS Ockhi developed on 29 November 2017 has passed through the southern tip of Kerala and resulted in the loss of life and severe damage to the properties (Mukherjee & Ramakrishnan, 2022;Sanap et al, 2020).…”

Introducing ‘Environmental Research: Climate’—a new journal devoted to understanding the causes, consequences and solutions of climate variability and change

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