Global Floods/Precipitation and Their Connections with the El Niño-Southern Oscillation During the TRMM Era

This study is focused on exploring global flood characteristics and variations using the outputs from the Dominant river Routing Integrated with VIC Environment (DRIVE) model. The high-quality satellite-based precipitation product, the TRMM/TMPA, is applied to drive the DRIVE model and also to examine global precipitation characteristics. Three flood indices are defined to represent flood frequency, duration and intensity at model grid-cells and at river basin/sub-basin scales. Spatial distributions and temporal variations of global flood events during the TRMM period are then examined and compared with those for precipitation. Climatologically, these flood indices generally have similar spatial patterns as precipitation. However, differences also exist in several areas including northern South America. The impact of large-scale climate modes such as the El Nino-Southern Oscillation (ENSO) on floods and precipitation during the TRMM period are then examined by estimating correlation relations of precipitation and flood indices with ENSO index at grids and over a variety of large river basins. ENSO can effectively influence precipitation and flood events in many regions and river basins. It is noted that during the peak ENSO season (DJF), simultaneous correlations of floods and precipitation with Nino 3.4 tend to be strong. Possible differences in the ENSO responses between flood indices and precipitation have also been explored and further assessed by focusing on how different their responses might be in different river basins. Differences between precipitation and floods, and possible differences in their response to ENSO will be further examined.