Title: Anomalous behaviour of Indian summer monsoon rainfall due to the change in some of the monsoon semi-permanent features in surplus and deficit years

Authors: Ghulam G. Zahid; Nuzhat Fatima; Aparna Sinha; Ajhar Hussain; Firoz Ahmad

Addresses: Department of Atmospheric and Ocean Sciences, Indian Institute of Technology, Bhubaneswar Orissa – 752050, India ' Department of Geology, Aligarh Muslim University, Aligarh – 202002, India ' Department of Geology, Aligarh Muslim University, Aligarh – 202002, India ' Department of Geology, Aligarh Muslim University, Aligarh – 202002, India ' Department of Management Studies, Faculty of Engineering, Indian Institute of Science (IISc), Bangalore – 560012, India; Department of Management Studies, Indian Institute of Technology, Roorkee – 247667, India

Abstract: The purpose of this research is to better understand the Indian summer monsoon's insufficient rainfall in 2002 and excess rainfall in 2007, as well as their relationship with large-scale circulation features and land-sea heating contrast. Zonal and Meridional wind at 850 Hpa and mean sea level pressure and monthly mean rainfall are the parameters used to describe the semi-permanent features and anomalous behaviour of ISMR. Over extensive portions of the Indian Ocean, Arabian Sea, and much of India, significant mean sea level pressure and rainfall anomalies are present. Negative rainfall anomalies prevailed over some parts in the centre of the monsoon core zone (MCZ). By evaluating the Somali jet, the Mascarene high and ISMR observed that heavy rainfall occurs in the MCZ. Mascarene high show stronger anticlockwise circulation in deficit year but due to the effects of El Niño wind and moisture transferred towards the East-Pacific region.

Keywords: Indian summer monsoon rainfall; ISMR; monsoon semi-permanent features; ENSO; convection; cross-equatorial low-level jet; monsoon core zone; MCZ.

DOI: 10.1504/IJHST.2024.140314

International Journal of Hydrology Science and Technology, 2024 Vol.18 No.2, pp.170 - 185

Received: 15 Jun 2022
Accepted: 09 Mar 2023
Published online: 02 Aug 2024 *

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