Evaluation And Correction Of TRMM 3B42 RT And CMORPH Precipitation Data In The Region Of China

Based on the observational precipitation data of 650 meteorological observation stations,on daily,monthly and yearly scales,linear correction and precipitation accuracy assessment were used for the two kinds of satellite data,TRMM 3B42 RT V7 and CMORPH satellite precipitation data respectively during 2003-2015 over China.Thus,the accuracy of satellite precipitation data is improved,and the ability of satellite precipitation data to monitor extreme rainstorms is also discussed.The conclusions are as follows:(1)In spatial distribution,the annual precipitation distribution of the two satellite data s(2003-2015) is similar to the ground observation results and they have a good correlation,which is basically in line with the spatial distribution characteristics of precipitation in China.(2)The monthly mean of two kinds of satellite data of TRMM 3B42 RT V7 and CMORPH are corrected.The correction formulas are y=2.46x+16.96 and y=3.19x+22.75 respectively.The average deviations between the two satellite observations and the ground stations are significantly lower (the average deviation of TRMM precipitation data and site precipitation data decreases from-45.5mm/month to-16.18mm/ month,and the average deviation of CMORPH precipitation data and site precipitation data decreases from-50.37mm/month to-17.36mm/month).(3)the ability of two kinds of data to detect moderate rain,heavy rain and total rainstorm is still limited.In the statistics of sprinkle days,CMORPH data are superior to TRMM 3B42 RT V7 data;TRMM 3B42 RT V7 data is better than CMORPH data for the detection of moderate rain,heavy rain and total rainstorm.Compared with the observational precipitation in the south of China,the corrected TRMM 3B42 RT V7 data are overestimated and CMORPH data is underestimated,but CMORPH data is superior to TRMM 3B42 RT V7 data in high altitude areas;in the area of abundant rainfall in southern China,the corrected TRMM 3B42 RT V7 data are overestimated and CMORPH data are underestimated compared with the observed rainfall in the stations.for high altitude areas,CMORPH data is superior to TRMM 3B42 RT V7 data,In some regions of northern China,the two satellite data are larger than the observed values.The corrected TRMM precipitation data are closer to the site observation in spring,autumn and winter,while the precipitation data of the CMORPH are closer to the observed precipitation in the summer.(4)On the daily,monthly and annual scales,the correlation coefficient,average deviation,average relative deviation and root mean square error between the observation and the two kinds of satellite datas were compared and analysised.On the whole,the TRMM precipitation data are better than that of the CMORPH precipitation data.(5)on monthly scales,by comparing and analyzing three different correction results(site by site correction,zoning correction and all China regional correction),the correction coefficients a and b of the two satellite datas in the whole China region are just within the range of correction coefficients a and b through site by site correction.While the correction coefficients a and b of partition correction did not within the range of a and b values through site by site correction in corresponding zones.(6)Through the study of Rainstorm in Beijing from July 21,2012 to 22,and the rainstorm in Xingtai,Hebei province from July 19,2016 to 21,it is found that the precipitation data of TRMM and CMORPH can monitor the rainstorm on the first day of the rainstorm,but both the two satellite data sare less than site observation data.