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Light rain events change over North America, Europe and Asia for 19732009

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Monday, 24 January 2011
Light rain events change over North America, Europe and Asia for 19732009
Washington State Convention Center
Yun Qian, PNNL, Richland, WA; and D. Gong and R. Leung

Analysis of daily precipitation data reveals different long-term trends of light rain events in North America, Europe and Asia, but overall a decrease trend is found from 1973-2009. In North America, most stations show a decrease trend for light rain but the same is also found for moderate and heavy rain. The overall light rain trend in Europe is not significant. In Asia, especially East Asia, the light rain days show an overwhelmingly decrease trend with high spatial coherency, while moderate and heavy rain events have increased, suggesting a remarkable shift from light to heavy rain. Although it has been argued that global warming may lead to a shift from light to heavy rain, regionally little correspondence is found between light rain trends and temperature/precipitable water trends. This argues for the need to include other factors such as circulation and aerosol changes that affect regional rain rates and cloud processes.