El Nino (Geography)
El Nino (Geography)
Why In News:
The India Meteorological Department (IMD) has confirmed the emergence of El Nino conditions in the Pacific Ocean, warning that it is likely to intensify during the Southwest (SW) monsoon season.
What is El Nino?
El Nino is the warm phase of the El Nino Southern Oscillation (ENSO), involving periodic warming of sea surface temperatures (SSTs) in the central and east-central equatorial Pacific Ocean.
During El Nino: Warm SSTs suppress the Walker Circulation, reducing the temperature gradient between the Indian Ocean and Pacific - this weakens the Indian Summer Monsoon.
Impact on India: Below-normal rainfall (drought-like conditions), especially in central and peninsular India.
Indian Ocean Dipole (IOD)
IOD (also called Indian Nino): A separate but related phenomenon in the Indian Ocean.
Positive IOD: Warmer western Indian Ocean, cooler eastern Indian Ocean - associated with above-normal rainfall in India (can counteract El Nino's negative effect).
Negative IOD: Associated with below-normal rainfall in India.
Key Facts for Prelims
SW Monsoon: Contributes about 70% of India's annual rainfall (June to September).
El Nino years and Indian droughts: 1987, 2002, 2009, 2014-15 were notable El Nino drought years in India.
IMD: India Meteorological Department, under Ministry of Earth Sciences.
Walker Circulation: Atmospheric circulation over the tropical Pacific; disrupted during El Nino.
Madden-Julian Oscillation (MJO): Intraseasonal oscillation (30-60 day cycle) that affects monsoon rainfall.