Comparison of precipitation datasets over the tropical South American and African Continents.

Six rainfall datasets are compared over the Amazon basin, the Northeast Brazil and the Congo basin. These datasets include three gauge-only precipitation products from the Climatic Prediction Center (CPC), Global Precipitation Climatology Center (GPCC) and Brazilian Weather Forecast and Climate Studies Center (CLMNLS), and three combined gauge and satellite precipitation datasets from the CPC Merged Analysis of Precipitation (CMAP), Global Precipitation Climatology Project (GPCP) precipitation, and Tropical Rainfall Measuring Mission (TRMM) product. The spatial pattern of the annual precipitation is consistently represented by these data, despite of the differences in methods and periods of averaging. Quantitatively, the differences in annual precipitation among these datasets are 3% over our Amazon domain (0-15S, 50-70W), 17% over the Northeast Brazil (5-10S, 35-45W) and 12% the Congo domain (5N-10S, 15-30E). However the seasonal differences were. Over the Amazon domain, the rainfall variations are well correlated between CPC, GPCC, TRMM, GPCP and GPCC (>0.9) except for the northwestern Amazon. Over the Congo basin, the correlation between these rainfall datasets is generally below 0.7. The Empirical Orthogonal Functions analysis suggests large discrepancies in interannual and decadal variations of rainfall among these datasets, especially for the Congo basin and for the South American region after 1998.