Detecting trends in tropical rainfall characteristics, 1979-2003

Analyses of two state-of-the-art, blended space-based and ground-based global rainfall data sets from the Global Precipitation Climatology Project (GPCP) and the Climate Prediction Center Merged Analysis Product (CMAP) reveal that there was a significant shift in the probability distribution functions of tropical rainfall during the period 1979-2003. This shift features a positive trend in the occurrence of heavy (top 10% by rain amount) and light (bottom 5%) rain events in the tropics during 1979-2003 and a negative trend in moderate (25-75%) rain events. These trends are consistent in both data sets and are in overall agreement with the Climate Research Unit's (CRU) gauge-only rainfall data over land. The relationships among the trends and the possible long-term changes in rainfall characteristics are discussed. Published in 2006 by John Wiley & Sons, Ltd.