Understanding future patterns of increased precipitation intensity in climate model simulations

In a future climate warmed by increased greenhouse gases, increases of precipitation intensity do not have a uniform spatial distribution. Here we analyze a multi-model AOGCM data set to examine processes that produce the geographic pattern of these precipitation intensity changes over land. In the tropics, general increases in water vapor associated with positive SST anomalies in the warmer climate produce increased precipitation intensity over most land areas. In the midlatitudes, the pattern of precipitation intensity increase is related in part to the increased water vapor being carried to areas of mean moisture convergence to produce greater precipitation, as well as to changes in atmospheric circulation. Advective effects, indicated by sea level pressure changes, contribute to greatest precipitation intensity increases (as well as mean precipitation increases) over northwestern and northeastern North America, northern Europe, northern Asia, the east coast of Asia, southeastern Australia, and south-central South America.