The Sea surface temperatures play a major role in global weather which influences two extreme phases of a naturally occurring climate cycle. I.e., El Nino/Southern Oscillation and La Nina. Both terms refer to large-scale changes in sea-surface temperature across the eastern tropical Pacific and the most powerful phenomenon of the Earth. These are best known for altering the climate across more than half of the planet that also impact the weather patterns. Here, we are giving the write-up on the ‘How does El Nino and La Nina impact on Indian Weather?’ for general awareness.
For better understanding about El Nino and La Nina phenomenon, we must know about Inter Tropical Convergence Zone (ITCZ). It is a low pressure zone located at the equator where trade winds converge, and so, it is a zone where air tends to ascend.
1. El Nino during winter causes warm conditions over the Indian subcontinent and during summer, it leads to dry conditions and deficient monsoon. Whereas La Nina results in better than normal monsoon in India.
2. India experienced deficient rainfall during El Nino years 2002 and 2009 whereas monsoon was normal during El Nino years 1994 and 1997. It means that in about 50 per cent of the year with El Nino during summer, India experienced droughts during monsoon.
3. Crops like Paddy, Maize, Groundnut, Guar, Castor, Tur, Moong and Bajra would suffer due to El Nino.
Other Factors that affect India’s rainfall pattern
1. North Atlantic Sea Surface Temperature
2. Equatorial SE Indian Ocean Sea Surface Temperature
3. East Asia Mean Sea Level Pressure
4. North Atlantic Mean Sea Level Pressure
5. North Central Pacific wind
Hence, we can say El Nino and La Nina impact greatly. El Nina resulted in a rise in warm air over the land and cooler moisture-bearing air blows in from the sea, bringing heavy rains or drought in the region. La Nina usually results in better than normal monsoon in India. But apart from these two, there are other factors that affect India’s rainfall pattern like North Atlantic SST, Equatorial SE Indian Ocean SST, East Asia Mean Sea Level Pressure, North Atlantic Mean Sea Level Pressure and North Central Pacific wind.