Wednesday 20 January 2016

El Niño, Rain & Heat: What’s the connection?

El Niño. The latest buzz word.  Lately we see and hear it mentioned almost on a daily basis. So, what exactly is it & how does it affect rain and rising temperature?

Simply put, El Niño makes an appearance when there’s changes in wind patterns over the equatorial Pacific.  It doesn’t happen all the time, roughly once every 2-7 years.  Its arrival is never precise.  It appears when it appears!

Back to El Niño.  When wind patterns over the Pacific Ocean changes, there will be changes in heat distribution to other parts of Earth, as well as changes in weather & climate. One of the changes in weather caused by an El Niño is a redistribution of rainfall around the Pacific.

What actually happens?
During normal conditions, strong easterly winds blow across the Pacific.  This pushes the warm water across the Pacific toward Indonesia and Australia. Just like warm water in the bathtub that produces clouds of steam in the bathroom, the warm water in the Pacific carries with it its rain clouds.

 Credit: NASA

As the warm water moves west, the nutrient rich cold water moves up along the coast of South America. This is called upwelling. Because fish follow this source of food, upwelling means lots of fish for the fishermen.

During El Niño conditions, the wind is not strong enough.  Sometimes it just stops.  Warm water hence stay closer to the South American Coast, cold water can't upwell & there’s no food for the fish. Instead, there is a lot of warm water piled up against the coasts of South & North America. Since the warm water always has its circle of clouds, there is heavy rain all along these coasts. 

When the rain is confined to the eastern side of the Pacific, western Pacific countries like Indonesia & Australia experience drought.

Credit: NASA

How does it affect us in South-east Asia?
According to the World Meteorological Organization (WMO), El Niño in South-east Asia is typically associated with drought. This is evidenced by the worst wildfires on record in Indonesia in 2015 with significant health repercussions, including an increase in acute respiratory infection.

In South Asia, El Niño conditions generated a weaker southwest monsoon than usual. El Niño is believed to have played a key role in the rainfall deficit in India.

Source: Adapted from “El Niño: Potential Asia Pacific Impacts,” NOAA Report (Oct. 2015)

Bear in mind that El Niño is not a regular cycle, or predictable like ocean tides.  So what’s in store for Malaysia? Let’s wait and see!

Shared by Azni Zainal Abidin
Guest Blogger

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