India’s Rainfall Shifts 2011-2020: GRL Study Using GSMaP-ISRO Data
Why in the news
A study published in Geophysical Research Letters looked at how India’s rain pattern, both quantity and timing, changed in the last decade compared with the one before.
Key facts
| Region | Rainfall change 2011-2020 | Peak rain timing |
|---|---|---|
| West-central India | About 2 mm per day higher | Delayed by 1-2 hours |
| Indo-Gangetic Plain | Slight rise, smaller than west-central | Advanced by 2-4 hours |
| Southern India | Slight rise, smaller than west-central | Not stated |
| Eastern India | About 1 mm per day lower | Not stated |
Vegetation and soil moisture
- NDVI (Normalized Difference Vegetation Index) in west-central India rose notably, from 0.2 to 0.4.
- More vegetation raises transpiration, adding water vapour to the air and influencing local climate.
- Soil moisture grew significantly in west-central India in step with rainfall, but fell markedly in the east.
Role of aerosols
- Timing shifts were linked to changes in aerosol loading.
- The Indo-Gangetic Plain, with higher aerosols, saw earlier peaks; lower-aerosol west-central India saw later peaks.
- A previous Beijing study found polluted conditions bring earlier rain peaks.
Significance
- Shows the interplay of climate, vegetation and aerosols in shaping rainfall.
- Matters for water management, agriculture and climate adaptation.
- Can improve rainfall prediction models and understanding of the hydrological cycle.
Exam angle
- Data set used: GSMaP-ISRO.
- Index term: NDVI measures vegetation density.
- Comparison decades: 2011-2020 against 2001-2010.