A Numerical Simulation Study On The Generation Of Urban Refined Land Use Data In Shanghai And Its Influence On Near Surface Meteorological Elements

The default land use data in WRF model is quite different from the actual land use situation.Therefore,it will affect the simulation effect.For this reason,many scholars put forward different schemes to update land use data before running the model.The simplest method is to use remote sensing data or existing datasets to update the expanding urban areas.Due to the heterogeneity of urban surface,it is suggested to subdivide the urban interior into three types of built-up areas.In recent years,with the concept of local climate zone(LCZ)put forward,researchers can divide cities into at most 10 kinds of urban functional areas with different properties.However,this method is rarely used in mainland China at present,and many existing studies cannot explain whether the improvement of accuracy in the model results is the function of refined classification or the role of urban area correction.And it cannot explain the advantage of LCZ data.Therefore,in this paper,3 kinds of land use datasets are generated by using remote sensing image,and introduced into the model.Considering the 2 factors of urban area expansion and refined classification of built-up areas,four cases are set up to simulate a high temperature weather process in August 2019.The results show that after updating the land use data in WRF,the simulation effect of temperature,relative humidity and wind speed are improved,among which the effect on temperature is the best.From the overall statistical indicators,the correction of urban area reduces RMSE by 0.77 ? and increases HR by 26%,which is the most simple and effective way to improve temperature simulation.The urban refined classification is the most effective way to improve the wind speed simulation,which can reduce RMSE by 0.14m/s at most and improve HR by 7%.In terms of daily variation and spatial distribution of temperature and wind speed,the refined classification after the correction of the urban area takes the heterogeneity of urban into account,so the improvement of the simulation results of temperature and wind speed is greater,and the more detailed the classification,the better the effect.Generally speaking,in this numerical simulation,LCZ scheme is better than other land use data updating schemes.In the future,if more accurate data of urban physical properties can be obtained,the advantages of LCZ scheme will be more prominent.