El Niño and La Ninã (ENSO)

Table of Contents

About El Niño and La Ninã (ENSO)

There are only six instances of La Ninã lasting for more than two years since 1950s, data with the India Meteorological Department (IMD) show.
The continuation of La Nina conditions spanning over 2 consecutive years is also called ‘Double Dip’ La Nina.

The Forecasting agencies from different countries have confirmed that the La Ninã conditions are here to stay till the end of 2022.
This year, India has received 3mm rainfall which was quantitatively 7 percent above the seasonal average till August 30. Out of the 36 states/Union Territories, 30 have received rainfall categorized as ‘normal’ or ‘excess’ or ‘large excess’, attributed to the La Ninã conditions.
For India, this could mean longer monsoons, prolonged heatwaves, higher rate of cyclone formation in Bay of Bengal and increased chances of flooding.

El Niño–Southern Oscillation (ENSO)

ENSO is an irregular periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and subtropics.
The warming phase of the sea temperature is known as El Niño and the cooling phase as La Niña.
These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

Basics of Comparision	El Niño	La Niña
Meaning	El Niño means Little Boy or Christ Child in Spanish.	La Niña means Little Girl in Spanish.
Sea surface of temperature	It represents the above-average sea-surface temperatures that periodically develop across the east-central equatorial Pacific.	It represents the periodic cooling of sea-surface temperatures across the east-central equatorial Pacific.
Pressure	It is laden with high air surface pressure in the western Pacific.	It contains low air surface pressure in the eastern Pacific
Formation	During El Niño, trade winds weaken. Warm water is pushed back east, toward the west coast of the Americas, resulting in a weaker Walker cell. Cold Peruvian (Humboldt) current gets replaced by warm Elnino (cormwell) current.	During La Niña events, trade winds are even stronger than usual, pushing more warm water toward Asia, resulting in a stronger Walker cell.
Period of occurrence	Typically occurs every 3-5 years and lasts 9-12 months.	Typically occur every 3-5 years and lasts 1-3 years.
Impacts	Droughts in eastern Australia Flooding in western South America Weak upwelling over the west coast of South America.	Excessive rainfall in the eastern Australia Drought conditions prevail in the South America Strong upwelling over the west coast of South America.
Impact of Indian Monsoon	The monsoon is affected so heavily that 70% reduction of the rainfall is expected. The winds doesn’t carry the moisture towards Indian landmass dueing El Nino causing deficiency in rainfall.	La Nina causes high temperatures over the Indian Ocean, off the Somalian coast and a comparatively better monsoon rains in India.