Regional Drought Modulation by ENSO and IOD as Indicated by the Standardized Precipitation Index
subject: Climatehydrology interactions; ENSO teleconnections; Indian Summer Monsoon; IOD; SPI
description: Understanding the modulation of drought by large-scale oceanatmosphere teleconnections is crucial for strengthening drought prediction and resilience in India. This study investigates the influence of the El NiSouthern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on meteorological drought characteristics across India from 1950 to 2024 using the Standardized Precipitation Index (SPI) at a 12-month timescale. Drought events were quantified in terms of frequency, duration, severity, and intensity and linked to ENSOIOD variability through composite, correlation, and mediation analyses. Results reveal that El Ni events consistently correspond to widespread and severe droughts, particularly over central and southern India, with drought frequency exceeding 30% and SPI < ?1.5. Conversely, La Ni phases enhance monsoon rainfall and alleviate drought conditions across much of the subcontinent. Spatial correlations demonstrate that ENSO exerts a stronger, more coherent influence on both rainfall and SPI than the IOD, while positive IOD phases can partly offset El Ni-driven drought in limited regions. Mediation and wavelet coherence analyses confirm ENSOs dominant control at interannual (48 year) timescales and reveal secondary, episodic modulation by the IOD. These findings highlight the complex, evolving dynamics between Pacific and Indian Ocean drivers in shaping Indias hydroclimate variability. The study underscores the need for integrated ENSOIOD monitoring and inclusion of multi-ocean indicators in Indias drought early warning and seasonal forecast frameworks. 2026 Binghamton University Libraries. All rights reserved.
creator: Tiwari, Arpit; Nanjundan, Preethi; Sharma, Tanu; Kumar, Ravi Ranjan; Ratna, Satyaban Bishoyi
source: Northeast Journal of Complex Systems;Volume;8;Issue;1;Article No.;3;
publisher: Binghamton University Libraries
date: 01-01-2026
rights: All Open Access; Gold Open Access
relation: ISSN: 25778439;
format: online
language: English
type: Article
coverage: Tiwari A., Christ (Deemed to be) University, Pune, Lavasa, 412112, India, Climate Research and Services, India Meteorological Department, Pune, Shivajinagar, 411005, India; Nanjundan P., Christ (Deemed to be) University, Pune, Lavasa, 412112, India; Sharma T., Climate Research and Services, India Meteorological Department, Pune, Shivajinagar, 411005, India; Kumar R.R., Climate Research and Services, India Meteorological Department, Pune, Shivajinagar, 411005, India; Ratna S.B., Climate Research and Services, India Meteorological Department, Pune, Shivajinagar, 411005, India