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La Nina to affect air quality in India during winter 2022: What does new study say?

La Nina to affect air quality in India during winter 2022: What does new study say?
La Nina to affect air quality in India during winter 2022: What does new study say?

Amitabh Sinha

Monsoon in India is known to be strongly influenced by El Nino and La Nina events, These El Niño and La Niña events cause the eastern Pacific Ocean to alternately warm and cool, affecting weather around the world. Even air quality in India may be affected by two weather phenomena, according to a new study by Indian researchers.

Read in English: La Nina impacted air quality in India in the winter of 2022: What a new study says

The study was conducted by Bangalore-based National Institute of Advanced Studies and Pune-based Indian Institute of Tropical Meteorology, Abnormal air quality in some Indian cities during winter 2022, La Niña prevailing at that time resultreported that it may be due to the peak event of

This is the first time that air quality in Indian cities has been linked to a La Nina phenomenon and indirectly linked to climate change that exacerbates El Niño and La Nina.

What is the connection between pollution and winter months in India??

From October to January, North Indian cities, Especially DelhiPMexperience very high concentrations of 2.5. Various meteorological factors such as temperature, Humidity, Density of air, Wind speed and direction play a role in trapping pollutants in the lower levels of the atmosphere. These factors also contribute to the transport of pollutants from other regions, particularly in Punjab and Haryana, to Delhi and its adjoining areas, generated by the burning of agricultural waste.

Due to the proximity of the western and southern parts of the country to the seas, They have relatively low levels of pollution.

However, The winter of 2022 showed a significant deviation from this normal. North Indian cities, including Delhi, were cleaner than usual, While the western and southern cities of Mumbai, Cities like Bengaluru and Chennai experienced worse than normal air quality.

In Ghaziabad PM2.5 concentrations are about 33% lower than normal in winter, The study also said that the concentration in Noida was 28% below normal. In Delhi it has decreased by around 10%. At the same time, The concentration in Mumbai rose by 30%, Also, Bengaluru recorded a 20% rise.

When researchers discovered that this anomalous behavior led to the possible effects of La Niña, they began to study it.

Wind direction

The most important factor in explaining the 2022 winter anomaly is a change in normal wind direction. At this time, The wind usually blows in a north-westerly direction: for example, Blows from Punjab towards Delhi and then across the Gangetic Plain. This is one of the main reasons why agricultural waste from Punjab and Haryana gets mixed in Delhi.

However, In the winter of 2022, Wind circulation was in north-south direction. Pollutants transported from Punjab and Haryana exclude Delhi and its surrounding areas, Flew from Rajasthan and Gujarat to southern regions (see map).

There is no change in local emission sources in Delhi and Mumbai. But additional pollution load from northern statesie Pollutants that usually land in and around Delhi, By a different route it reached Peninsular India, Some also landed in Mumbai,” Gufran Baig, lead researcher and country’s leading coin pollution expert explained.

The local circulation of wind near Mumbai also had an irregular behavior that year. Wind currents alternate from land to sea every few days. Wind carries pollutants out of the city as it blows from land to sea. However, In the year 2022, Instead of changing direction every four to five days, Winds persisted in one direction for a week or more than 10 days, This has led to heavy pollution in Mumbai.

La Niña and climate change

Baig said the wind activity in both cases was associated with an extended La Niña, This is in the winter of 2022, lasted an unusually long three years.

“When we used global wind circulation data resulting from La Niña in our computer models, We found that wind patterns emerged over the Indian region similar to the observed changes. When models were run with data from previous years, When there is no strong La Niña, These anomalous air patterns have disappeared. It showed strong sensitivity to La Niña conditions,” Baig said.

Baig said not all La Nina events cause significant changes in air circulation over India. “This is a particularly strong phenomenon. The impact of the wind cycle became apparent only in the third year of La Niña. So, There can be many consequences,” Baig said.

Baig said it is not yet fully known whether El Nino will have an adverse effect on air quality over India.

Changes in wind patterns were not the only reason for the unusual trends in air quality that year, the study said. It refers to local weather conditions unrelated to La Niña, This may also lead to reduction of pollutant concentrations in North India.

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The article is in Tamil

Tags: Nina affect air quality India winter study

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