Assessment of multiple precipitation products over major river basins of China

As the largest component of the global water cycle, precipitation plays a critical role in determining available water in the terrestrial ecosystems. Numerous precipitation products have been generated during the last decades, but they differ substantially in terms of their spatial and temporal variations. In this study, we compared seven precipitation products covering ten major river basins of China from 1980 to 2007 and found large differences among the products. Overall, the Global Precipitation Climatology Center (GPCC) product shows the highest correlation with rain gauge measurements and lowest estimation errors over the ten basins. The performances of other products also clearly differ over the ten basins, and the maximum estimates were 1.27 +/- 0.21 times the minimum estimates in terms of interannual variability in precipitation. Based on the seven products, we generated a new precipitation dataset using the Bayesian model averaging method. Compared with all the individual products, the new dataset indicates the decreased root mean square error and increased coefficient of correlation. In the statistical analysis of the weight for each of the products, the GPCC product contributed the maximum weight among almost all river basins. Both the ERA-Interim and MERRA products contributed the minimum weights, being less than 10 %. Our results highlight the need to investigate and improve the performance of precipitation products when evaluating the regional water balance.