Research Of Precipitation Estimation Method Based On TRMM Satellite Data Across China

Tropical Rainfall Measuring Mission satellite,which has the properties of high spatial,temporal resolution and wide coverage,can make up the shortcomings of conventional meteorological data in distribution of time interval and space,becoming an important source of meteorological data.Since the development of the weather observation service in that area,scholars form various countries have done great research in meteorological satellite rainfall estimation methods,proposing some related new methods to estimate the rainfall and launching some relevant Service tests.By taking Chinese area as the research object,supported by remote sensing and geographic information technology,the method of geographical differences analysis calibration is introduced in this paper for solving the disadvantages of statistical precipitation downscaling model of Chinese area,and apply the double smoothing method to regional precipitation estimation aiming at improving the estimation precision of precipitation and strengthening the characteristics of spatial distribution of precipitation for the west areas with sparse distribution of automatic meteorological stations.The main conclusions are as follows:(1)Comparing with the precipitation data of automatic meteorological station,the validation results show that the TRMM 3B43 precipitation products display a good correlation with it,but some problems also exist,the estimation of TRMM 3B43 products is relatively accurate for frontal precipitation?low altitude areas as well as spring and autumn.But the estimation error is relatively big in river and lake areas?high altitude areas and summer seasons with complex precipitation distribution.(2)Apply spatial statistical downscaling precipitation estimation of geographical differences analysis to TRMM 3B43 precipitation products at the resolution of 0.25°,finally the improved monthly precipitation estimation at the resolution of lkmxlkm can be got.The results show that downscaling monthly precipitation estimation which adopts the geographical differences analysis calibration is the most accurate,its coefficient of determination is higher,and rms error?absolute error?deviation is smaller.The spatiotemporal distribution of calibrated monthly precipitation data keeps the same with uncalibrated TRMM precipitation products,and almost consistent with the hyetometer observation data.(3)Double smoothing method is introduced for solving the problem of sparse spatial distribution of automatic meteorological station in western China.The results show that the average deviation?rms error are reduced after taking the fusion method proposed in this paper for the areas with sparse distribution of automatic meteorological station,and the correlation coefficient is increased to 0.455,this method is more accurate in estimating the heavy rain;the method proposed in this paper is more reasonable and effective compared with the method of literature[50]in efficiency coefficient and the spatial distribution of deviation;finally,visual test shows that the method proposed in this paper is more accurate in estimating the precipitation and it has better visual performance in areas with sparse observations.