Global Satellite Mapping of Precipitation (GSMaP)-ISRO

Global Satellite Mapping of Precipitation (GSMaP)-ISRO: A study examined spatial rainfall trends across India and found changes in daily rainfall amounts and timing of peak rainfall across different regions in the 2011–2020 decade compared to 2001–2010. The study used GSMaP-ISRO data to analyse rainfall patterns.

• About Global Satellite Mapping of Precipitation (GSMaP)-ISRO: It is a precipitation product for the Indian subcontinent, developed through an agreement between ISRO and the Japan Aerospace Exploration Agency (JAXA).

o Algorithm Technology: The GSMaP algorithm, designed by JAXA, uses microwave radiometers and cloud motion data from Geostationary Infrared (IR) technology.

• Key Study Observations (Rainfall Trends 2011–2020 vs 2001–2010):

o Rainfall Increase: West-central India experienced a slight increase in rainfall (~2 mm/day) during 2011–2020.

üThough Indo-Gangetic Plain and southernmost parts had increased rainfall, it was less than west-central India.

o Vegetation and Soil Moisture Linkage: The increase in rainfall over west-central India is linked to increased vegetation cover.

üTranspiration Role, increased vegetation causes more transpiration, releasing water vapour and influencing summer monsoon rainfall via evapotranspiration.

o Sea vs Land Timing: Peak rainfall time is in the morning over the Arabian Sea and Bay of Bengal, and in the afternoon over inland areas.

o Aerosol Influence on Rainfall Timing: Aerosol loading influences rainfall peak timing.

o Indo-Gangetic Plain: Higher aerosol loading likely caused early peak rainfall in Indo-Gangetic Plain, while lower aerosol levels led to late peak rainfall in west-central India during 2011–2020.