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‘Triple dip’ La Nina and its impact on India’s monsoon

  • Published
    23rd Sep, 2022
Context

Australia’s Bureau of Meteorology (BOM) predicted that a third consecutive event of La Niña could be underway.

About

What is La Niña?

El Nino-Southern Oscillation (ENSO)

  • ENSO is the interaction between the atmosphere and ocean in the tropical Pacific.
  • It is a series of linked weather and ocean-related phenomena.
  • La Niña involves the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean coupled with changes in the tropical atmospheric circulation (winds), pressure, and rainfall.
  • It usually has the opposite impact on weather and climate as El Niño.
  • La Niña is characterized by lower-than-normal air pressureover the western Pacific.
  • These low-pressure zones contribute to increased rainfall. 
  • La Niña years are associated with above-average trade winds, pushing the warmer waters towards Asia and drawing in cooler than normal water temps to the equatorial pacific. 
  • Causes: La Niña is caused by a build-up of cooler-than-normal watersin the tropical Pacific, the area of the Pacific Ocean between the Tropic of Cancer and the Tropic of Capricorn.
    • Unusually strong, eastward-moving trade winds and ocean currents bring this cold water to the surface, a process known as
  • Effects:La Niña affects; patterns of rainfall, atmospheric pressure and global atmospheric circulations.

What does a triple La Niña mean?

  • A triple La Niña or a ‘triple dip’ La Niña is a rare occurrence, lasting for three years in a row. It has happened only twice since 1950.
  • On the contrary, the occurrence of two consecutive La Niña winters in the Northern Hemisphere is common.

Impact of El Nino and La Nina

  • El Nino is associated with drought or weak monsoons.
  • La Nina is associated with strong monsoons and above average rains and colder winters.

Impact on India

  • Monsoon: India may experience an extended monsoon lasting up to October due to La Niña.
  • Agriculture:La Nina could have negative impacts on Indian agriculture.Farmers will be at risk of losing their standing Kharif crops if it rains during this period.

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