Regional and remote influences of ocean‐atmospheric processes on northeast monsoon rainfall during 2021 over India

Vijaya Bhaskara Rao, S. and Pradhan, Prabodha Kumar and Raman, Mekalathur Roja and Kumar, Vinay and Sunilkumar, Khadgarai and Jena, Babula and Koteswara Rao, Kundeti (2024) Regional and remote influences of ocean‐atmospheric processes on northeast monsoon rainfall during 2021 over India. International Journal of Climatology, 44 (1). pp. 17-38. ISSN 0899-8418

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Abstract

Severe rainfall during the recent northeast monsoon season (October, November and December) in 2021 caused unexpected disasters (triggered flooding and landslides) in the pilgrim city of Tirupati and the metropolitan city of Chennai over the peninsular of India (PI). The remote and regional influence of several ocean‐atmospheric climate indices on northeast monsoon rainfall (NEMR) during the OND season is investigated to understand the contributory mechanisms of extreme rainfall events over the PI during 2021. The interannual variability of NEMR and its relationship with the OND sea surface temperature (SST) anomaly over the Niño3.4 and Indian Ocean Dipole (IOD) regions are considered. In addition, SST anomalies over the Bay of Bengal (BoB), such as east BoB (EBoB), east equatorial Indian Ocean (EEIO) and their gradients (GSST) connections with NEMR, are also examined. The impact of Siberian High (SH), Western Pacific High (WPH), Arabian Sea Surface Pressure (ASSP), easterly waves (EW) and land surface temperature contrast (LSTC) is also analysed and incorporated to find a specific linkage with NEM 2021. The results show that excess NEMR during OND 2021 is suggestively associated with favourable large‐scale conditions like negative IOD and the La Niña phase over the Indo‐Pacific region. In November 2021, two deep depressions made landfall over Tamil Nadu (within the latitude of 11°–13°N) and over adjoining areas, which caused copious amounts of rainfall (maximum ~90 mm·day −1 ), leading to flooding conditions over Tirupati and Chennai. During the NEM season, abundant warming of BoB and weak vertical wind shear, along with negative anomalies of ASSP, modulated the cyclonic activities that enhanced the sufficient moisture transports from BoB to the PI. The MSLP anomalies over the ASSP region depict a significant correlation (−0.47) with the interannual variability of NEM as compared to SH and WPH during the OND season of 2021.

Item Type:	Article
Authors:	Vijaya Bhaskara Rao, S. and Pradhan, Prabodha Kumar and Raman, Mekalathur Roja and Kumar, Vinay and Sunilkumar, Khadgarai and Jena, Babula and Koteswara Rao, Kundeti
Document Language:	Language English
Subjects:	Natural Sciences > Earth sciences > Geology, hydrology, meteorology Natural Sciences > Earth sciences > Geology, hydrology, meteorology > Climatology and weather
Divisions:	Azim Premji University - Bengaluru > School of Climate Change and Sustainability
Full Text Status:	None
URI:	http://publications.azimpremjiuniversity.edu.in/id/eprint/6969
Publisher URL:	https://doi.org/10.1002/joc.8313

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