Evaluation and hydrological applications of TRMM rainfall products over the Mekong River basin with a distributied model

This paper presents an evaluation of two different global satellite precipitation products (TRMM 3B42v7 and TRMM 3B42 RT) during 2001-2004 over the Mekong River basin for hydrologic applications with using a distributed hydrological model. The result demonstrates that generally 3B42 V7 is closer to rainfall field interpolated by gauge data and has a better performance in runoff simulation than 3B42 RT, which overestimates 15.6% annual rainfall over the basin. In addition, a pixel-point comparison with the gauge data shows that, calibration against ground rain gauge observation greatly reduce the bias in 3B42 V7. On the contrary, 3B42 RT shows region-dependent bias: overestimation in the upper Mekong; underestimation in the middle basin. Such region-dependent bias of 3B42 RT is propagated into the simulated discharge, which makes the simulated discharge overestimate at all the stations especially at the upstream stations. Regard to the seasonal variations, both 3B42 V7 and RT have a good estimation during wet seasons with Pearson correlation coefficient (CC) higher than 0.60. The discharge simulation reveals that 3B42 V7 is able to monitor the streamflow at daily scale over whole basin and that 3B42 RT performs well during wet season in lower basin. It implies there is potential to make near real time hydrological simulation through using 3B42 RT.