| Precipitation is the most basic link of the process of hydrolic cycle and,precipitation is also the important meteorological elements,and more over is the important factors that influence the hydrologic cycle,hydrological forecasting,water resources evaluation and management of water resources,water cycle and water balance calculation.Therefore,accurate knowledge of precipitation information plays an important role in the study of atmospheric circulation in different space-time scales.The current sources ways of getting precipitation data include ground weather station observation and ground-based rain radar.Meteorological sites for direct precipitation measurement has the advantage of accuracy,but its disadvantage lies in that it can only obtain the points precipitation data of the corresponding station,the rainfall data interpolation's quantity based on the distribution of the meteorological sites,and the interpolation accuracy limits its application scope.The ground-based rain radar can obtain the precipitation information with higher resolution of space-time,but the theoretical foundation is complex and the range of observation is also very limited.In recent years,the development of remote sensing satellite and geographic information system has provided a new methods and means for precipitation data obtaining.TRMM precipitation data from Remote sensing satellite not only has the higher accuracy(0.25°× 0.25 °)character and relatively large observation range(50°S-50°N),but also can get the meteorological data on that sparsely populated places,such as marine area,plateau,desert areas and some other no meteorological sites places,thus can greatly complement the information lackage of time and space distribution of rainfall.But,because of it is an indirect observation method,the precision of satellite remote sensing precipitation data need to be verified by ground station precipitation data,so as to achieve the consistency even replaced each other between two kind of data.This paper takes the northern shaanxi,Guanzhong area and southern shaanxi as research areas,choose 47 weather stations' observed precipitation data of different time scales,to look for the differences between these real values and meteorological satellite TRMM precipitation data,thus to verify the deviation between the measured rainfall data,on the basis of the analysis based on the monthly precipitation data the relative deviation of time and space distribution characteristics of precipitation in shaanxi,the contingency table method,the evaluation methods of observation and the correlation coefficient test the accuracy of the shaanxi province three region TRMM data,build the TRMM precipitation data as the independent variable of the measured rainfall deviation estimation model and example verification.The results show that on the whole,the different time scales of TRMM data have better correlation with site measured rainfall data and the data accuracy is higher,more than on numerical site measured precipitation is low,the error is relatively small;Specifically,the correlation coefficients of > for >,the MRE value of MRE,the MRE value of the MRE.At the same time,in the study area,meteorological satellites have relatively high accuracy in measuring accuracy in small rain and heavy rain,and the deviation is relatively small.However,the measuring accuracy of medium rain is relatively low and the deviation is relatively large.Results show that the TRMM's estimate of annual precipitation and the observed precipitation has the very high consistency in Shanxi Province,shaanxi average correlation coefficients of above 0.85,shows a significant correlation.As a whole,TRMM data value are less than the measured value;Precision of different time intervals data analysie tell that summer and fall is better than winter and spring,and deviation of TRMM data is less in water rich year than in waterless year.In northern Shaanxi,monthly TRMM data is smaller than the real value,the maximum deviation is 8.24%;In Guanzhong area,monthly TRMM inversion is also smaller than the real value,the maximum deviation is 4.37%;But in southern Shaanxi,monthly TRMM version is bigger than the real value,the maximum deviation is 1.42%.It shows that these formular could be used in the actual month precipitation estimation under different typical frequency in every areas of Shaanxi province.North south overall TRMM satellite datum's precision in Shaanxi shows the character of higher in the south,but lower in the north,conforms the changing rule on TRMM satellite's data observation precision.Research results available can help to obtain a more accurate estimate on rainfall data and the effective inversion to the non-material area of Shaanxi province. |
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