IMP

Why India is watching the El Niño forecast with bated breath

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by

Neha Raj
in

Syllabus: Important Geophysical phenomena such as earthquakes, tsunamis, Volcanic activity, cyclones, etc.

Source: The Hindu 

Context: The La Niña itself is going on for a record-breaking third consecutive year; forecasts for 2023 are predicting that El Niño– will occur with more than a 50% probability.

About El Niño and La Niña:

  • El Niño refers to a band of warmer water spreading from west to east in the equatorial Pacific Ocean. Similarly, a La Niña occurs when the band of water spreads east-west and is cooler.
  • Both phenomena affect the weather worldwide and can have drastic effects on economies that depend on rainfall.
  • Together, El Niño and La Niña make up a cyclical process called the El Niño Southern Oscillation (or ENSO).

Issues in predicting El Niño:

  • El Niño forecasts before spring tend to be notoriously unreliable due to a so-called ‘spring predictability barrier’. 
  • The tropical Pacific Ocean soaks up heat like a sponge and builds up its volume of warm water. During El Niño, this warm water spills from the western part of the Pacific Ocean to the eastern part.
  • But the earth has had three straight La Niña years, which means the Pacific’s warm-water volume is fully loaded and is likely to birth an El Niño soon.

 Effects on the northern Indian Ocean:

  • It tends to produce the largest deficit in the monsoon, approximately 15%.
  • The vertical shear (change in the intensity of winds from the surface to the upper atmosphere) tends to be weaker as well. This in turn can favour enhanced cyclogenesis, i.e. cyclone formation.

Prelims Link: UPSC 2017

With reference to the ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting the Indian monsoon, which of the following statements is/are correct?

  1. IOD phenomenon is characterized by a difference in sea surface temperature between the tropical Western Indian Ocean and the tropical Eastern Pacific Ocean.
  2. An IOD phenomenon can influence an EI Nino’s impact on the monsoon.

Select the correct answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

 

Solution: B