Behind Australia’s “Once in a Century” Floods: La Niña?

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Much of the Brisbane's suburbs are submerged in the flood-water

The Queensland floods in Eastern Australia have been the stuff of nightmares but now a NASA satellite can help explain where the floods are happening at all.

The cause of the extreme flooding is thought to be the La Niña event which is ongoing in the Pacific Ocean. La Niña, Spanish for “the child girl”, is a weather phenomenon that occurs shortly after the better know El Niño event, indicated by warmer temperature in the south Pacific and weaker trade winds, which causes more arid conditions than usual in Australia, Indonesia and India.

(Photos on Flooding in Australia Spreads.)

In contrast, La Niña is a swing out in the opposite direction before normal climate conditions resume. It sees a cooling of the subsurface Pacific Ocean which contrasts with the warmer summer climate in the Western Pacific. This causes the air pressure to drop and a rise in precipitation levels in the same countries.

The effects of the phenomena have been highlighted with the serious and deadly weather conditions in Eastern Australia and Sri Lanka and could possibly be partly responsible for the flooding in Brazil, though there is less evidence to support that theory. The La Niña has been snapped by NASA‘s Ocean Surface Topography Mission (OSTM)/Jason-2 satellite which shows images that indicate the strongest La Niña event in the 50 years that they have been recorded. Thermal images taken of the South Pacific show a huge mass of cooler than usual water, which explains some of the weather events in the affected countries.

(More on Hundreds Die in Brazilian Mudslides.)

“Although exacerbated by precipitation from a tropical cyclone, rainfalls of historic proportion in eastern Queensland, Australia have led to levels of flooding usually only seen once in a century,” said David Adamec, Oceanographer at NASA’s Goddard Space Flight Center, Greenbelt, Md. “The copious rainfall is a direct result of La Niña’s effect on the Pacific trade winds and has made tropical Australia particularly rainy this year.”

While local weather forecasts in Queensland are cautiously optimistic, the La Niña in the South Pacific is expected to last until at least mid-fall.