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Increased rainfall in tropics caused by more frequent big storms

25 March 2015

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A new study based in part on NASA satellite data has shown that an increase in large, well-organised thunderstorms is behind increased rainfall in the wettest regions of the tropics.

Many scientists have long thought that in a warming world some regions are likely to see more rain because a warmer atmosphere is capable of holding more water vapour. The idea seemed to be supported by recent observations showing strong precipitation increases in the wettest tropical regions, sometimes referred to as a 'rich-get-richer' pattern.

Joint research from the Australian Research Council Centre of Excellence for Climate System Science (ARCCSS) and NASA published online in Nature reveals that rainfall increases seen in places such as the western Pacific in recent decades are actually due to large storms - what the authors call "organised deep convection" - happening more frequently, rather than from individual storms producing more rain.

"The observations showed the increase in rainfall is directly caused by the change in the character of rain events in the tropics rather than a change in the total number of rain events," said lead author Jackson Tan, who conducted this research while at Australia's Monash University but now works at NASA's Wallops Flight Facility, Wallops Island, Virginia. "What we are seeing is more big and organised storms and fewer small and disorganised rain events."

Source: National Aeronautics and Space Administration (NASA)

Image credit: Flickr user barto - Rain cloud seen from above

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