Assessment of Precipitation in the Three Gorges Reservoir Area with TRMM and CMORPH Satellite Data
Based on the TRMM and CMORPH remote sensing satellite precipitation data from 1998 to 2016 and the observation data in the Three Gorges Reservoir Area in the same period, this paper evaluates the local precipitation changes in the Three Gorges Reservoir Area by comparing the precipitation changes of the main stream and the branch stream as well as the far and the near meteorological stations, and by comparing the characteristics of precipitation, precipitation days and precipitation intensity before and after impoundment. The results show that the interannual variation characteristics of TRMM and CMORPH satellite precipitation data in the Three Gorges Reservoir Area are generally consistent with those of meteorological observation stations. The inversion effect of TRMM on the daily scale is slightly lower than that of CMORPH, and that of CMORPH on the seasonal scale is slightly lower than that of TRMM. The inversion effects of both satellite data on winter precipitation are weak.The precipitation variations of the main stream and the branch stream stations in the Three Gorges Reservoir Area are generally the same, having strong interannual variation characteristics. Compared with CMORPH, TRMM can roughly reproduce the interannual variation characteristics of precipitation at the main stream and branch stream stations. The interannual fluctuation amplitude of CMORPH precipitation is generally larger than that of meteorological stations. Compared with the time period before and after water storage (1998-2003 and 2004-2016), the CMORPH distribution is closer to the variation trend of the stations than TRMM in terms of the inversion effect of the precipitation intensity, precipitation days, seasonal precipitation frequency and total amount of precipitation at different grades, and the inversion effect is slightly better than TRMM. However, the precipitation frequency and distribution of the two satellites are similar to observation. The errors of the stations do not change significantly before and after impoundment. In addition, the meteorological stations, TRMM and CMORPH data show that the ratio of annual precipitation in the far and the near reservoir areas of the Three Gorges fluctuates stably after impoundment, which indicates that there is no obvious change in precipitation in the vicinity of the Three Gorges Reservoir after impoundment.