Evaluation of satellite rainfall products over the Congo Basin

This paper evaluates nine satellite rainfall products and the Global Precipitation Centre Climatology (GPCC) gauge data set over the Congo Basin. For the evaluation the reference data set is a newly created, gridded gauge data set based on a gauge network that is more complete than that of GPCC in recent years. Gridding was achieved via a climatic reconstruction method based on principal components, so that reliable estimates are rainfall are available even in the data-sparse central basin. Several products show excellent agreement with the NIC131 reference data set. These include CHIRPS, PERSIAN, GPCP, TRMM and, to a lesser extent, GPCC. The most poorly performing products in this region include CMORPH, ARC2, CMAP and to a lesser extent RFE2. In all cases, the performance of the ten produces evaluated is notably poorer in recent years (1998 to 2010), when the station network is sparse, than during the period 1983 to 1994, when the dense station network provides reliable estimate of rainfall. All products do reasonable in reproducing the seasonal cycle and the latitudinal gradients of rainfall. Estimates of interannual variability show more scatter among the various products and are less reliable. Overall, the most important results are demonstrating the strong impact that actual gauge data have on the various products and the need to have access to such products, in order to produce reliable rainfall estimates form satellite.