El Nino and India

Subject : Geography

Section :Physical geography

Context: India should brace for dry and hot spring-summer, El Nino, say experts.

More on the News:

Very little rainfall and warmer-than-normal temperatures projected for February as well as a declining La Niña indicate a hot and dry spring and summer months for most of India.
United States Global Forecasting System data showed a spike in maximum temperatures in the northwest and some parts of central, eastern and southern India starting from February 17, 2023.
The reason for this sudden spike in temperatures is
- a strong upper level westerly jet that seems to be setting up lower-level winds that are sweeping in warm ocean and desert winds.
- The high-pressure region is causing subsidence of air as well as enhancing the influx of dry winds from the northwest into India.
During spring and summer seasons, there are concerns regarding the decline of the La Niña conditions by March-April and the development of El Niño conditions later in the year, which could mean further rise in temperatures and subsequent heat waves.
Forecasting model of the United Kingdom Met Agency about the 5°C barrier being temporarily breached for the average temperature anomaly for 2024 due to the prospective El Niño.

More about El Nino:

The ENSO cycle-

El Niño is characterised by warmer-than-average waters in the central and eastern tropical Pacific and a slowdown of trade winds (which blow east to west), and La Niña by cooler-than-average waters and intensified trade winds.
A neutral phase emerges when conditions are neither warm nor cool.
El Niño, La Niña and neutral phases are a part of ENSO, climate phenomena that alter atmospheric circulation.
This impacts temperature and precipitation across the globe.

El Nino impacts on India:

In a normal monsoon year (without El Nino), the pressure distribution is as follows:
The coast of Peru in South America has a higher pressure than the region near northern Australia and South East Asia.
The Indian Ocean is warmer than the adjoining oceans and so, has relatively lower pressure. Hence, moisture-laden winds move from near the western Pacific to the Indian Ocean.
The pressure on the landmass of India is lower than on the Indian Ocean, and so, the moisture-laden winds move further from the ocean to the lands.
If this normal pressure distribution is affected for some reason, the monsoons are affected.
El Nino means lesser than average rains for India. Indian agriculture is heavily dependent on the monsoons and because of this, lesser rainfall during the monsoons generally translates to below-average crop yields.

Triple-dip La-Nina-

A “triple-dip” La Nina is a multiyear cooling of the surface temperature of the equatorial Pacific Ocean, which can cause droughts, fierce winds and heavy rainfall.
According to WMO, the current La Nina is projected to span three consecutive northern hemisphere winters.
Since 1950, the Earth has witnessed a triple La Niña thrice, including the current one.
A La Niña phase four years in a row has not been recorded so far.