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<p>This study investigates modulation of extreme rainfall over India by Madden Julian Oscillation (MJO) using 50-year (1974–2024) high-resolution daily rainfall dataset and Real time Multivariate MJO (RMM1 and RMM2) indices. Rainfall events were categorized by intensity and analyzed across eight MJO phases using composite anomalies, circulation diagnostics and frequency based trend analysis. Results reveal that MJO Phases 1, 2 are associated with enhanced convective activity and a higher frequency of extreme and very heavy rainfall events. The result shows MJO phase 5 and phase 6 are associated with high intensity of extreme rainfall and very heavy rainfall, especially over Indo—Gangetic Plain, central India and northeastern regions. These phases align with MJO convective envelope's presence over Indian Ocean, promoting favourable conditions (OLR anomaly and geopotential rainfall anomaly shows negative) for deep convection and large-scale precipitation. Phase 7 and phase 8 show less rainfall, with more dry spells and negative rainfall anomaly dominating over peninsular and western India. The spatial patterns of maximum rainfall intensity also show significant attenuation during these later phases. The findings underscore MJO critical role in modulating intraseasonal hydroclimatic extremes over India and highlight its potential in improving sub-seasonal to seasonal rainfall forecasts, particularly for disaster preparedness and climate risk management in a warming climate. </p>

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Modulation of Indian Rainfall Extremes by Madden–Julian Oscillation Phases

  • 期刊论文

  • 发表日期：

    2026年6月24日

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  • Rajeev Bhatla,
  • Purnima Yadav,
  • Aashna Verma

摘要

This study investigates modulation of extreme rainfall over India by Madden Julian Oscillation (MJO) using 50-year (1974–2024) high-resolution daily rainfall dataset and Real time Multivariate MJO (RMM1 and RMM2) indices. Rainfall events were categorized by intensity and analyzed across eight MJO phases using composite anomalies, circulation diagnostics and frequency based trend analysis. Results reveal that MJO Phases 1, 2 are associated with enhanced convective activity and a higher frequency of extreme and very heavy rainfall events. The result shows MJO phase 5 and phase 6 are associated with high intensity of extreme rainfall and very heavy rainfall, especially over Indo—Gangetic Plain, central India and northeastern regions. These phases align with MJO convective envelope's presence over Indian Ocean, promoting favourable conditions (OLR anomaly and geopotential rainfall anomaly shows negative) for deep convection and large-scale precipitation. Phase 7 and phase 8 show less rainfall, with more dry spells and negative rainfall anomaly dominating over peninsular and western India. The spatial patterns of maximum rainfall intensity also show significant attenuation during these later phases. The findings underscore MJO critical role in modulating intraseasonal hydroclimatic extremes over India and highlight its potential in improving sub-seasonal to seasonal rainfall forecasts, particularly for disaster preparedness and climate risk management in a warming climate.