Abstract Rainfall accompanying North Indian Ocean cyclonic disturbances (or CDs) at times can cause significant hazards, often producing flash floods. In a changing climate scenario, the CD activity and, thereby, the associated rainfall are expected to change. The present study emphasizes the effects of Indian Ocean Dipole (IOD), El-Niño Southern Oscillation (ENSO), and Madden–Julian Oscillation (MJO) in governing the variability of CD-contributed rainfall (CDR) during the pre- and post-monsoon periods for the years from 1980 to 2021. The total accumulated rainfall is perceived to be higher over Andhra Pradesh and Odisha for all the considered events in the pre-monsoon season, except in Gujarat and the northeast parts of Odisha during La-Niña. During the post-monsoon period, the accumulated precipitation is generally greater in Andhra Pradesh, Odisha, and Tamil Nadu, although the annual variability indicates less frequency of yearly CD days during La-Niña. Nonetheless, a higher CDR is received during the pre-monsoon months, especially during La-Niña periods. However, the post-monsoon months experience a greater contribution, while higher CD days are observed. A similar trend is observed during MJO days, with significant CDR accompanied by a higher number of CD days in the post-monsoon months, although an identical outcome is realized during the pre-monsoon with less number of CD days in the pre-monsoon months. Negative IOD and La-Niña events favoured greater CDR with appreciable CD days during post-monsoon. In the recent decade, a considerable CDR has been realized during positive IOD events. Principal component analysis endorses MJO to be a dominant factor for governing the CDR over the Indian landmass, although the intensity and frequency of contributing CDs are significant. Research Highlights <UnorderedList Mark="Bullet"> <ItemContent> •Effects of Indian Ocean Dipole (IOD), El-Niño Southern Oscillation (ENSO), and Madden–Julian Oscillation (MJO) on the variability of cyclonic disturbance contributed rainfall (CDR) is analyzed during 1980–2021. </ItemContent> <ItemContent> •Impact of MJO, ENSO and IOD on CDR delivery over Indian landmass is noteworthy, specifically in the states of Andhra Pradesh, Odisha, Tamil Nadu, and Gujarat. </ItemContent> <ItemContent> •The ‘climate modes’ have a large dependency on seasonal characteristics while regulating the CDR over Indian landmass. </ItemContent> <ItemContent> •MJO followed by ENSO, governs CDR variability over Indian landmass by modulating the NIO CD frequency, intensity and duration. </ItemContent> </UnorderedList>

Assessing IOD, ENSO, and MJO effects in governing the cyclonic disturbances contributed rainfall variability over India during 1980–2021

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发表日期：

2025年11月20日

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Jagabandhu Panda,
Geo Tom,
Kasturi Singh,
Debashis Paul,
Ipshita Bhasi

摘要

Abstract

Rainfall accompanying North Indian Ocean cyclonic disturbances (or CDs) at times can cause significant hazards, often producing flash floods. In a changing climate scenario, the CD activity and, thereby, the associated rainfall are expected to change. The present study emphasizes the effects of Indian Ocean Dipole (IOD), El-Niño Southern Oscillation (ENSO), and Madden–Julian Oscillation (MJO) in governing the variability of CD-contributed rainfall (CDR) during the pre- and post-monsoon periods for the years from 1980 to 2021. The total accumulated rainfall is perceived to be higher over Andhra Pradesh and Odisha for all the considered events in the pre-monsoon season, except in Gujarat and the northeast parts of Odisha during La-Niña. During the post-monsoon period, the accumulated precipitation is generally greater in Andhra Pradesh, Odisha, and Tamil Nadu, although the annual variability indicates less frequency of yearly CD days during La-Niña. Nonetheless, a higher CDR is received during the pre-monsoon months, especially during La-Niña periods. However, the post-monsoon months experience a greater contribution, while higher CD days are observed. A similar trend is observed during MJO days, with significant CDR accompanied by a higher number of CD days in the post-monsoon months, although an identical outcome is realized during the pre-monsoon with less number of CD days in the pre-monsoon months. Negative IOD and La-Niña events favoured greater CDR with appreciable CD days during post-monsoon. In the recent decade, a considerable CDR has been realized during positive IOD events. Principal component analysis endorses MJO to be a dominant factor for governing the CDR over the Indian landmass, although the intensity and frequency of contributing CDs are significant.

Research Highlights

•Effects of Indian Ocean Dipole (IOD), El-Niño Southern Oscillation (ENSO), and Madden–Julian Oscillation (MJO) on the variability of cyclonic disturbance contributed rainfall (CDR) is analyzed during 1980–2021.

•Impact of MJO, ENSO and IOD on CDR delivery over Indian landmass is noteworthy, specifically in the states of Andhra Pradesh, Odisha, Tamil Nadu, and Gujarat.

•The ‘climate modes’ have a large dependency on seasonal characteristics while regulating the CDR over Indian landmass.

•MJO followed by ENSO, governs CDR variability over Indian landmass by modulating the NIO CD frequency, intensity and duration.