Comparison between the active tropical cyclone seasons over the Arabian Sea and Bay of Bengal

Abstract

Climatologically, tropical cyclone (TC) activity in the North Indian Ocean (NIO) is asymmetric between the Arabian Sea (AS) and Bay of Bengal (BoB) basin. For the 172 TCs formed over NIO during 1983–2015, only 56 formed over AS and the rest (116) over BoB. During the period, AS was very active in a few years (but with quiet BoB season), and the opposite occurred in some others. It is found that this contrast occurred mostly during the post‐monsoon season of October–December. The meteorological and climate factors that accounted for these contrasting AS and BoB TC seasons are analysed. While climate variability such as the El Niño Southern Oscillation and Indian Ocean Dipole have known influences to NIO TC activity, results reveal that no single climate mode can well explain the TC development concentrating on AS or BoB only. Instead, it is found that variability of the northeast monsoon is an important factor responsible for the difference between the two basins. Excess moisture is available over the AS due to anomalous low‐level flow from the equatorial IO in the years in which there are more TCs in that basin, and dryer condition is over the BoB. In these years, there is likely excess northeast monsoon rainfall. The relationship is opposite between post‐monsoon BoB TC activity and the northeast monsoon. Nevertheless, the anomalous flow during active AS TC seasons is similar to that occurs during positive Indian Ocean Dipole, and thus this climate variability may be responsible for redistributing the moisture content in the NIO.

North Indian Ocean tropical cyclone activity inCMIP5experiments: Future projections using a model‐independent detection and tracking scheme

“…The NIO basin experiences two active periods of TC activity, pre‐monsoon (April to June) and post‐monsoon (October to December) with a lull in activity during the peak monsoon season (July to September). Two sub‐regions can be defined divided by the Indian sub‐continent that experience asymmetric activity (Sattar and Cheung, 2019), the more active Bay of Bengal to the east (Alam et al ., 2003) where TCs can impact the coastlines of India and Bangladesh (Singh et al ., 2000), and the quieter Arabian Sea to the west (Mohapatra et al ., 2014) where TCs can sometimes reach the Arabian Peninsula (i.e., Oman and Yemen, see Figure 1 for geographical location of these countries).…”

Potential Impacts of Anthropogenic Forcing on the Frequency of Tropical Depressions in the North Indian Ocean in 2018

“…We focused on the observations of tropical depressions in the North Indian Ocean during 1980-2018, because satellite monitoring started from the late 1970s [5,16] and the data are considered reliable only from 1983 [6]. Figure 1 shows the 14 tropical depressions with their tracks and intensity during 2018; among them, seven developed into cyclonic storms, with five intensifying into severe cyclonic storms-three of which became very severe cyclonic storms.…”

“…Moreover, the intensity of pre-monsoon and post-monsoon tropical cyclones in the Bay of Bengal has increased over the past several decades [13,14]. The SST warming anomaly in the central Pacific, known as El Niño Modoki, can also enhance Indian Ocean cyclones [15,16]. Climate model experiments have projected an increase in cyclone frequency over the Arabian Sea and a decrease in the Bay of Bengal [17].…”

Assessment and Attribution of Mangrove Forest Changes in the Indian Sundarbans from 2000 to 2020

“…The Bay of Bengal experiences 7% of the major cyclones of the world [90]. Over the last 120 years, there has been a 26% increase in the number of very severe cyclonic storms over the northern Bay of Bengal [91] and increases in both frequency and intensity have been observed for the last two decades in particular [92][93][94].…”