Understanding the post‐monsoon tropical cyclone variability and trend over the Bay of Bengal during the satellite era

Abstract

An effort is made to investigate the tropical cyclone (TC) variability over the Bay of Bengal in the warming climate scenario during the satellite era (1979–2018). In this study, the authors investigate interannual variations in the overall capacity of the Bay of Bengal (BoB) basin in the post‐monsoon season to produce either intense or moderate TCs. Globally accepted and widely used metrics accumulated cyclone energy (ACE) and power dissipation index (PDI) are used to examine the energy and damage generated by TCs. A statistical change‐point analysis is conducted to detect the shift in the tropical cyclone frequency and ACE during the study period, indicating the year 1999 as a change point. The results show the increasing trend in ACE in the BoB during the post‐monsoon season with a statistical significance of 95%. On the contrary, the overall frequency is almost unchanged but has shown an increasing trend in the last decade of the study period. Additionally, atmospheric and ocean factors influencing the TC intensity are investigated by applying principal component analysis for three categories of TCs, viz. the very severe cyclonic storm, severe cyclonic storm, and cyclonic storm. Implementation of principal component analysis and correlations of maximum sustained wind speed (MSW2; intensity) with relative vorticity, minimum sea‐level pressure (MSLP), sea‐surface temperature (SST), specific rainwater content, and vertical wind shear revealed relative vorticity as the most dominating parameter amongst all governing factors which determine the final intensity of the BoB TCs. On the contrary, SST shows the different nature of the relationship with different TC categories.

The appraisal of tropical cyclones in the North Indian Ocean: An overview of different approaches and the involvement of Earth’s components

“…In addition, there are studies done in the past to understand the impact of TC on the BoB region. The findings from the studies confirm the rise in the NIO SST (Tiwari et al, 2021). Mishra et al (2020) reported a strong role of ARB warming on increasing weather extremes.…”

“…EDITED BY which results in the development of a low-pressure area (Tiwari et al, 2021). TCs have a horizontal scale of hundreds to thousand kilometres extending throughout the troposphere's height (Wang et al, 2012).…”

“…The combination of these two variables drives the bimodal seasonal cycle of TCs' in both the ARB and the BoB. Tiwari et al (2021) investigated the characteristics of post-monsoon season TCs' over the BoB from 1979 to 2018 using various metrices such as ACE and PDI. They also used correlation and principal component analysis on the VSCS, SCS, and CS category TCs, taking into account SST, vertical wind shear, MSW, minimum sea level pressure (MSLP), relative vorticity, and specific rainwater content, among other parameters and revealed that relative vorticity is the most influential among all the controlling elements that impact the final intensity of the BoB TCs'.…”

Ocean Mixed Layer Response to Two Post‐Monsoon Cyclones in the Bay of Bengal in 2018

“…Several studies indicate an increase in frequency and intensity of the post-monsoon cyclones in the past decade (Balaguru et al, 2014;Jyoteeshkumar Reddy et al, 2021;Mohanty et al, 2012;Singh et al, 2000;Tiwari et al, 2022). Balaguru et al (2014) attribute this increase to a rise in SST, ocean heat content, and moist static energy in the eastern Bay.…”

Stochastically perturbed physics-tendencies based ensemble mean approach in the WRF model: a study for the North Indian Ocean tropical cyclones

“…parameters that are used to address the TC's intensity(Tiwari et al, 2021). Hence, the analysis has been conducted to examine the prediction of selected TCs' intensity signified by 6-hourly MSLP (MSLP error) and…”