La Nina

La Nina

Subject :Geography

Section: Climatology

Context:

The Australian Bureau of Meteorology has declared a fresh La Nina alert in the tropical Pacific, which means there is a 70 per cent chance (about triple the normal likelihood) of another La Niña forming later this year. This is even as an existing long-drawn La Nina, thought to be firing up a concurrent Indian monsoon, had approached closure but has shown signs of revival during the last month or two.

• According to experts La Nina, which is touted by researchers variously as the second or third-longest in history.
• It is likely driving this year’s monsoon to a fourth successful one on the trot.

Concept :

About La Nina :

• It means the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean, together with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall.
• It has the opposite impacts on weather and climate as El Niño, which is the warm phase of the El Niño Southern Oscillation (ENSO).

Weather  Changes due to La Nina :

• The Horn of Africa and central Asia will see below average rainfall due to La Niña.
• East Africa is forecast to see drier-than-usual conditions, which together with the existing impacts of the desert locust invasion, may add to regional food insecurity.
• It could also lead to increased rainfall in southern Africa.
• It could also affect the South West Indian Ocean Tropical Cyclone season, reducing the intensity.
• Southeast Asia, some Pacific Islands and the northern region of South America are expected to receive above-average rainfall.
• In India, La Niña means the country will receive more rainfall than normal, leading to floods.