Monsoon Updates

The Atlantic Niño’s role in India’s erratic monsoon

Note4Students

From UPSC perspective, the following things are important :

Prelims level : El nino and La nina

Mains level : Paper 1- Challenges in monsoon prediction

Context

Last month, farmers from Madhya Pradesh threatened to take IMD to court for the inaccurate monsoon forecast this year. A question was also raised in Parliament about whether the Arctic warming had led to an erratic monsoon this year.

Understanding the role of Atlantic Niño in monsoon prediction

  • Monsoon predictions are a monumental challenge, especially when it comes to the spatial distribution and the northward migration of the monsoon trough.
  • Forecast models tend to rely heavily on El Niño for monsoon predictions.
  • But only about 50 per cent of the dry years are explained by El Niño.
  • Clearly, Atlantic Niño is a significant player in monsoon evolution and models and forecasters must pay attention to this Atlantic teleconnection.
  • Atlantic Niño is El Niño’s little cousin in the Atlantic, also known as the Atlantic Zonal Mode.
  • Indian scientists from INCOIS have argued that the Atlantic Niño is in fact predictable up to three months in advance.
  • Every few years, from June to August, there is a warming in the eastern equatorial Atlantic, which does not get as much attention as its big brother El Niño.
  • The biggest rainfall deficits from the Atlantic Niño tend to occur over the Western Ghats and the core monsoon zone.

How Atlantic Niño plays a role if Indian and Atlantic Oceans are not connected?

  • The Atlantic and Indian Oceans are not directly connected in the tropics via the ocean.
  • The Atlantic Niño affects the monsoon by producing atmospheric waves, which propagate into the Indian Ocean.
  • These waves affect air temperatures over the Indian Ocean and influence the land-ocean thermal contrast as well as Low Pressure Systems (LPS).

Way forward

  • Overall, monsoon prediction skill has gone up in the IMD but even a 70 per cent accuracy means the forecasts will be wrong 30 per cent of the time.
  • Many of the Atlantic Niños occur during non-El Niño years and this offers a window of opportunity to increase forecast skills based on the accurate prediction of the Atlantic Niño.

Conclusion

No forecasts will ever be 100 per cent accurate. Climate scientists are also aware of the monsoon prediction challenge and they will continue to try to improve monsoon forecasts.

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Back2Basics:  El Niño and La Niña

  • These periodic weather patterns occur as a result of fluctuating ocean temperatures in one part of the world, namely the east-central equatorial Pacific Ocean.
  • This can lead to extreme weather.
  • When warm water builds up along the central and eastern tropical Pacific Ocean, an El Niño occurs.
  • Conversely, when cool water builds up along the same region, a La Niña occurs with the opposite impact.
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