Why in news
- Meteorological forecasts indicate concentrated late-season rainfall over East and Central India during the southwest monsoon withdrawal phase.
- Climate models indicate strong multi-year El Niño conditions persisting in the equatorial Pacific Ocean.
Key terms
El Niño
Periodic warming of central and eastern equatorial Pacific waters that alters global atmospheric circulation.
Monsoon Withdrawal
Process where south-westerly winds retreat from northern India, replaced by north-easterly continental air masses.
Walker Circulation
East-west tropical atmospheric circulation cell driven by ocean temperature gradients across the Pacific.
ENSO
El Niño-Southern Oscillation, a coupled ocean-atmosphere climate phenomenon involving sea temperature and air pressure shifts.
What is the spatial pattern of late-monsoon rain?
- As the southwest monsoon begins its retreat from Northwest India, precipitation systems shift eastwards and centralwards across the subcontinent.
- Convective activity during the withdrawal phase often brings localized heavy rainfall events to East-Central river basins.
El Niño persistence and atmospheric mechanism
- El Niño involves anomalous warming of sea surface temperatures in the central and eastern tropical Pacific Ocean.
- Extended multi-year El Niño phases weaken atmospheric Walker circulation, disrupting normal tropical monsoon precipitation cycles across South Asia.
Why it matters
- Extended Pacific warm events increase risk of inter-annual rainfall variability and agricultural water stress across rainfed farming zones.
- Understanding monsoon withdrawal dynamics is crucial for reservoir management and Rabi crop planning.
Prelims facts
- El Niño typically results in weakened Indian southwest monsoon rainfall due to suppressed convection over South Asia.
- Monsoon withdrawal begins traditionally from northwest India in September as continental high pressure builds.
Mains discussion
- Impact of persistent multi-year ENSO anomalies on Indian climate resilience and agricultural production.
- Adaptation strategies required for rainfed agriculture under heightened monsoon variability.
Source: Economic Times India
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