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Increased Summer Monsoon Rainfall over Northwest India caused by Hadley Cell Expansion and Indian Ocean Warming.
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  • Ligin Joseph,
  • Nikolaos Skliris,
  • Dipanjan Dey,
  • Robert Marsh,
  • Joel Jean-Marie Hirschi
Ligin Joseph
School of Ocean and Earth Science, University of Southampton

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Nikolaos Skliris
School of Ocean and Earth Science, University of Southampton
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Dipanjan Dey
School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar
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Robert Marsh
University of Southampton
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Joel Jean-Marie Hirschi
National Oceanography Centre
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The Indian summer monsoon precipitation trend from 1979 to 2022 shows a substantial 40% increase over Northwest India, which is in agreement with the future projections of the Coupled Model Intercomparison Project 6 (CMIP6). The observationally constrained reanalysis dataset reveals that a prominent sea surface warming in the western equatorial Indian Ocean and the Arabian Sea might be responsible for the rainfall enhancement through strengthening the cross-equatorial monsoonal flow and associated evaporation. We show that the cross-equatorial monsoon winds over the Indian Ocean are strengthening due to the merging of Pacific Ocean trade winds and rapid Indian Ocean warming. These winds also enhance the latent heat flux (evaporation), and in combination, this results in increased moisture transport from the ocean toward the land.