Influence of seasonal variability in the environmental factors on tropical cyclone activity over the Bay of Bengal region

• Published in: Spatial information research (Online) Vol. 29; no. 5; pp. 673 - 684
• Main Authors: Pal, Abhisek, Chatterjee, Soumendu
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.10.2021; 대한공간정보학회
• Subjects: Database Management; Earth and Environmental Science; Geographical Information Systems/Cartography; Geography; Remote Sensing/Photogrammetry; 공학일반; Environmental variability; Tropical cyclone; Bay of Bengal; Genesis Potential Index; Seasonality
• ISSN: 2366-3286; 2366-3294
• DOI: 10.1007/s41324-021-00383-9

The genesis of tropical cyclones over the Bay of Bengal region showed a significant amount of both spatial and temporal variability. Mean tropical cyclone genesis locations were shifted southward from July to December. The tropical cyclone activity was greatly suppressed during the monsoon (June–September) season compared to the post-monsoon (October-December) season. A Genesis Potential Index is presented to demonstrate the spatial and temporal alteration in the environmental factors contributing to the tropical cyclone genesis. Here we used six environmental factors such as instability, relative humidity, sea surface temperature, relative vorticity, mean sea level pressure and vertical wind shear. All of the six environmental factors showed a considerable amount of month-wise variability over the Bay of Bengal region from monsoon to post-monsoon season. We observed that during the monsoon season, instability, relative humidity and sea surface temperature were very favorable for tropical cyclone genesis, but the tropical cyclone frequency was very low compared to the post-monsoon season due to very high vertical wind shear and low relative vorticity. On the other hand, reduced vertical wind shear and increased relative vorticity overwhelmed the effect of reduced instability and increased relative humidity and favored tropical cyclone genesis during the post-monsoon season.