Why in the News?

A recent study published in Geophysical Research Letters revealed changes in both the amount and timing of rainfall using GSMaP Data between the decades 2001-2010 and 2011-2020.

About Global Satellite Mapping of Precipitation (GSMaP)

• GSMaP is a specialized precipitation product developed through collaboration between ISRO (Indian Space Research Organisation) and JAXA (Japan Aerospace Exploration Agency).
• It provides high-resolution precipitation data with a 0.1° x 0.1° grid and one-hour temporal resolution, focusing on the Indian subcontinent since March 2000.
• The data supports rainfall trend analysis, climate modelling, and water resource management.

Key Findings of the Study:

• Rainfall Trends:
  • West-Central India: Increased daily rainfall (2 mm/day) from 2011-2020 compared to 2001-2010.
  • Eastern India: A decrease of ~1 mm/day in rainfall during the same period.
  • Regional Shifts: Northeastern and eastern India saw decreased rainfall, while the Indo-Gangetic Plain and southern India experienced increases.
• Vegetation & Soil Moisture:
  • West-Central India saw an increase in vegetation (NDVI from 0.2 to 0.4) and soil moisture linked to increased rainfall.
  • Eastern India had decreased soil moisture during the same period.
• Shifts in Peak Rainfall Timing:
  • Indo-Gangetic Plain: Peak rainfall advanced by 2-4 hours.
  • West-Central India: Peak rainfall delayed by 1-2 hours.
• Factors responsible for this Shift:
  • Higher soil moisture supports rainfall, while reduced moisture, particularly in eastern India, decreases rainfall.
  • Higher aerosol concentrations in polluted areas like the Indo-Gangetic Plain lead to earlier rainfall peaks.
  • Changes in atmospheric circulation, topography, and coastal influences also affect rainfall distribution and timing.

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