关键词: TRMM3B43降水数据, 塔里木河流域, 精度评估, 时空变化

Abstract: Tarim River basin, a typical arid area in northwestern China, faces serious water shortage that has badly restricted local ecological balance and socio-economic development. Since precipitation is the main source of surface water and the beginning of water cycle, to learn the spatial-temporal distribution of precipitation is rather important for further water usage. However, the precipitation gauge stations are dramatically sparse in this basin due to economic imperative, high elevation, complex topography and severe climate, especially in mountains and desert of the basin, making the precise estimation of spatial-temporal precipitation distribution in this region a difficult problem. However, there is great potential to carry out hydrological prediction in ungauged basins by using satellite estimate precipitation data. As a precipitation radar satellite, TRMM(Tropical Rainfall Measuring Mission)has collected plentiful fine spatial-temporal precipitation data, which means to use the TRMM precipitation data to study hydrological and climatic characteristics in the Tarim River basin is feasible. But it is necessary to check the accuracy of TRMM data before using it. In this study, TRMM Multi-Satellite Precipitation Analysis(TMPA)3B43 product is evaluated by using the gauge precipitations from 24 weather stations(2000-2013)in Tarim River basin. Results show as follows:(1)compared with the 24 rain gauges, TRMM3B43 data displayed good accuracy in the whole study area at annual time scale. The average Bias is 19.02% and about 60% of TRMM precipitation is higher than that from weather stations.(2)Most sites have a goodness of fit at monthly time scale except a few sites(Yutian, Qiemo and Wuqia). The goodness of fit between TMPA precipitation and observed precipitation is better in spring. In summer and autumn, the TRMM precipitation data is underestimated, and in winter, it is overvalued.(3)Precipitation in Tarim River basin shows a gradual increasing trend from southeast to northwest, and especially dominant on the edge of the northwest, forming a relatively abundant water belt. When stretching towards the desert hinterland area, precipitation shows a decreasing trend.(4)Changes of the maximum precipitation position in the region have certain regularity in a year:every winter, it moves from west to north in the basin, and stays in the northern basin in summer. When autumn comes, it moves back to northwest. On a whole, the TRMM 3B43 data can express the spatial and temporal distribution of precipitation in the basin. And the larger time scale is, the more accurate TRMM data will show, for part of the error will be offset. That is why TRMM data of a river basin has the highest precision in annul precipitation, while relatively lower in quarterly precipitation and lowest in monthly precipitation. The Tarim River lies between Tianshan mountains and Kunlun mountains, and located in the mid-latitude westerlies control area of northern hemisphere, so changes of the basin rainfall distribution and the maximum precipitation area are influenced by the terrain and seasonal water vapor sources.

Key words: TRMM3B43 Data, Tarim River basin, accuracy assessment, spatio-temporal variation