Regional and temporal variability of Indian summer monsoon rainfall in relation to El Niño southern oscillation

K S Athira; M K Roxy; Panini Dasgupta; J S Saranya; Vineet Kumar Singh; Raju Attada

doi:10.1038/s41598-023-38730-5

Regional and temporal variability of Indian summer monsoon rainfall in relation to El Niño southern oscillation

Sci Rep. 2023 Aug 4;13(1):12643. doi: 10.1038/s41598-023-38730-5.

Authors

K S Athira^{1

2

3}, M K Roxy⁴, Panini Dasgupta^{4

5

6}, J S Saranya^{4

7

8}, Vineet Kumar Singh^{4

9

10}, Raju Attada¹¹

Affiliations

¹ Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India. [email protected].
² Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India. [email protected].
³ College of Climate Change and Environmental Sciences, Kerala Agricultural University, Thrissur, India. [email protected].
⁴ Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India.
⁵ Department of Meteorology and Oceanography, College of Science and Technology, Andhra University, Visakhapatnam, India.
⁶ Future Innovation Institute, Seoul National University, Siheung, 15011, Seoul, Republic of Korea.
⁷ College of Climate Change and Environmental Sciences, Kerala Agricultural University, Thrissur, India.
⁸ School of Earth and Environmental Sciences/Research Institute of Oceanography, Seoul National University, Seoul, 08826, Republic of Korea.
⁹ Department of Atmospheric and Space Sciences, Savitribai Phule Pune University, Pune, India.
¹⁰ Typhoon Research Center, Jeju National University, Jeju, South Korea.
¹¹ Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India.

Abstract

The Indian summer monsoon rainfall (ISMR) exhibits significant variability, affecting the food and water security of the densely populated Indian subcontinent. The two dominant spatial modes of ISMR variability are associated with the El Niño Southern Oscillation (ENSO) and the strength of the semi-permanent monsoon trough along with related variability in monsoon depressions, respectively. Although the robust teleconnection between ENSO and ISMR has been well established for several decades, the major drivers leading to the time-varying relationship between ENSO and ISMR patterns across different regions of the country are not well understood. Our analysis shows a consistent increase from a moderate to substantially strong teleconnection strength between ENSO and ISMR from 1901 to 1940. This strengthened relationship remained stable and strong between 1941 and 1980. However, in the recent period from 1981 to 2018 the teleconnection decreased consistently again to a moderate strength. We find that the ENSO-ISMR relationship exhibits distinct regional variability with time-varying relationship over the north, central, and south India. Specifically, the teleconnection displays an increasing relationship for north India, a decreasing relationship for central India and a consistent relationship for south India. Warm SST anomalies over the eastern Pacific Ocean correspond to an overall decrease in the ISMR, while warm SST anomalies over the Indian Ocean corresponds to a decrease in rainfall over the north and increase over the south of India. The central Indian region experienced the most substantial variation in the ENSO-ISMR relationship. This variation corresponds to the variability of the monsoon trough and depressions, strongly influenced by the Pacific Decadal Oscillation and North Atlantic Oscillation, which regulate the relative dominance of the two spatial modes of ISMR. By applying the PCA-Biplot technique, our study highlights the significant impacts of various climate drivers on the two dominant spatial modes of ISMR which account for the evolving nature of the ENSO-ISMR relationship.