| Precipitation is an important parameter in the global energy cycle and the main source of river runoff.How to obtain high-precision precipitation data is an important research direction in the field of meteorology,hydrology and other related science and technology.Although the traditional observation data of surface rainfall station and surface rainfall radar can provide high-precision rainfall information,they have some defects,which limit their application in hydrological simulation.In recent years,the development of satellite technology provides an important way for people to obtain large-scale and high-precision precipitation.At present,there are many kinds of satellite precipitation data,but each has its own advantages and disadvantages.Multi source rainfall fusion is an important means to integrate the advantages of multiple satellite rainfall products to achieve higher precipitation retrieval accuracy.This study is based on the two spatial differences in the accuracy of the two representative precipitation data IMERG and GSMaP of the Global Precipitation Measurement(GPM),and studies the fusion algorithm of the two satellite precipitation data.Specifically,with China's mainland as the research area,a study on the fusion of precipitation data from IMERG and GSMaP satellites from 2001 to 2019 was carried out based on the nine major river basins.The accuracy of the fusion result product is evaluated through the observation of rainfall data from the weather station,and based on the fusion results to carry out research on the extraction of rainstorm information,in order to obtain the temporal and spatial law of the evolution of heavy rain in China's mainland.Get the following conclusions:(1)Quantitatively evaluate the fusion of precipitation and precipitation data from IMERG and GSMaP satellites through ground stations,the results show: The accuracy of fusion precipitation in the nine major watersheds has been improved differently,The ability to detect rainfall has been enhanced.The correlation coefficient(Correlation Coefficient,CC)and Root Mean Square Error(RMSE)of satellite precipitation fusion products have been optimized to different degrees in different watersheds relative to the two original data;The precipitation hit rate(Probability of Detection,POD)and Critical Success Index(CSI)of the fusion data have been improved.Through fusion calculation,the ability to capture and detect precipitation is improved.(2)Take the fusion data from 2001 to 2019 as input data,and extract the rainstorm information based on the rainstorm extraction program.Obtained the heavy rain information in China's mainland in the past 19 years,and analyzed its distribution and occurrence rules.The results show: my country's heavy rains are prone to and concentrated in the Yangtze River Basin,the Pearl River Basin and the Southeastern China Mainland.The maximum number of heavy rains is summer,and the range of heavy rains is wider.The range of rainstorms in autumn is greater than that in spring and winter.However,the overall number of torrential rains and the total amount of torrential rains are the lowest in the four seasons.The center of the heavy rainfall and the number of heavy rains in China's mainland in the past19 years is located in the Yangtze River Basin.(3)By comparing the rainstorm extraction results of IMERG,GSMaP and fusion data,it is found that the monitoring ability of the three kinds of precipitation data for rainstorm is slightly insufficient;however,through the fusion calculation,the rainstorm hit rate of the fusion precipitation data has been slightly improved. |
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