Climatic Impacts of Enso (El-Nino- Southern Oscillation) Events on Spatial Rainfall Variability across India

Abstract

Aims: This study examined associations between El Niño–Southern Oscillation (ENSO) phases, meteorological subdivision rainfall variability, and historical drought and flood occurrences across India during 1950–2017. Study Design: A retrospective climatological assessment of ENSO classifications and spatial rainfall departures. Place and Duration of Study: India, 1950–2017. Methodology: Niño 3.4 sea surface temperature anomalies and historical rainfall records were used to classify El Niño, La Niña and neutral years and to compare rainfall responses across Indian meteorological subdivisions. Rainfall departures were examined against the long-term annual rainfall baseline, and historical drought and flood occurrences were considered in relation to ENSO phases. The analysis included spatial comparisons of phase-mean rainfall anomalies and correlation analysis. Results: El Niño years generally coincided with reduced rainfall, including departures of −8.32% in Bihar, −8.74% in Punjab, −8.74% in Gujarat and −9.58% in Kerala. Positive departures nevertheless occurred in Jammu and Kashmir (+4.25%) and West Rajasthan (+0.04%). During La Niña years, positive rainfall departures were reported in Punjab (+10.67%), Bihar (+9.75%) and the Andaman and Nicobar Islands (+5.88%). Other subdivisions exhibited negative departures, indicating substantial regional variation. Historical drought and flood occurrences showed associations with ENSO phases, although these observations do not establish causation. Conclusion: ENSO provides useful context for understanding spatial rainfall variability across India, but its phases do not determine rainfall conditions uniformly across subdivisions. Regional climatic influences must also be considered when interpreting rainfall anomalies and potential hydrological risks.