Grid-based Estimation Of Monthly Precipitation In Watershed Based On Remote Sensing Precipitation Products And Ground Observation Data

The Yangtze River is the largest river in China,and the Yellow River is the second largest river.The distribution of precipitation affects the environment and climate change in the Yangtze and Yellow River basins.The simulation study of precipitation factors has an important impact on ecology,hydrology and meteorology.In this paper,IMERG precipitation products,TRMM precipitation products,and FY-2F precipitation products are used as precipitation trends.The stepwise regression method based on region and month is used to determine the model parameters combined with DEM data,ground weather station data.Then a model for estimating monthly precipitation under complex terrain in the Yangtze and Yellow River basins was established.The model has revised the three precipitation products of IMERG,TRMM and FY-2F,and found that the model estimation results can reflect the spatial distribution characteristics and time distribution of monthly precipitation in the Yangtze and Yellow River basins.At the same time,it can reflect the local distribution law.The model estimates that the IMERG,TRMM and FY-2F monthly precipitation results are closer to ground observation precipitation.The paper mainly draws the following conclusions:(1)The paper evaluates the accuracy of three precipitation products,IMERG,TRMM and FY-2F.The results show that IMERG precipitation products and TRMM precipitation products have higher precision and better correlation with ground precipitation.IMERG and TRMM precipitation products can accurately describe the spatial distribution characteristics and seasonal distribution of the Yangtze and Yellow River basins.However,the FY-2F precipitation product is less correlated with ground precipitation.Three precipitation products were studied as the precipitation trend term of the model.(2)Dominant precipitation orientation indicates the source of water vapor during precipitation.The dominant precipitation orientation is calculated from the meteorological station precipitation data,the site latitude and longitude data,and the aspect data.Terrain correction items for precipitation are established based on data such as dominant precipitation orientation,elevation,slope,and aspect.(3)Three precipitation products are used as model precipitation trend items,combined with precipitation topographic correction factor,the model of monthly precipitation under the complex terrain of the Yangtze River Basin and the Yellow River Basin is established,and the model coefficient is determined by the stepwise regression algorithm of regional and monthly.The results show that after the model is revised,the annual average relative error of the three precipitation products in the Yangtze River Basin is less than 30%,and the average relative error of the three precipitation products in the Yellow River Basin is about 30%.It shows that the model can effectively correct the precipitation products,and the estimated precipitation can reflect the characteristics of local precipitation.(4)This paper compares and analyzes the results of three precipitation products as model trend items.It can be found that whether it is the Yangtze River Basin or the Yellow River Basin,from the perspective of trend items,IMERG precipitation products have the highest precision,followed by TRMM precipitation products,and FY-2F precipitation products have the lowest precision.