Impact of the Satellite-Gauge Based Precipitation Assimilation on Regional Downscaling

As recent studies have shown, the use of a regional model to downscale the large-scale analyses marginally improves simulated precipitation fields. This study investigates the impact of assimilating combined satellite- gauge products on a regional climate simulation over South America. The authors seek to recover the precipitation patterns during January of 2004, when precipitation analyses are available daily from a high- resolution, satellite-gauge based analysis over the continental South America. Here, precipitation assimilation is only effectuated in the same time scale as the rainfall analysis. As will be shown, rain rate assimilation not only increases the regional model precipitation simulation skill, but also improves the simulation of other variables influenced by the precipitation, as the South American circulation reveals precipitation patterns related to the low level flows. Due to the potential impact on land surface variables, improvements in monthly to seasonal predictions are expected.