Sensitivity And Mechanism Analysis Of CWRF Model Land-atmosphere Coupling To Different Physical Process Parameterization Schemes

Based on the Climate extension of the Weather Research and Forecasting model(CWRF),data of 27 experimental set members with different parameterization schemes,and the two sets of ERA5 and MERRA-2 reanalyzes data in the summer of 1990-2011(June,July,and August),the impact of different parameterization schemes on the land-atmosphere interaction is studied.Daily variation analysis is used to evaluate the simulation performance of CWRF.Then three indicators are set to measure the land-atmosphere coupling : the correlation between soil moisture and latent heat,the correlation between latent heat and lifting condensation level,and the correlation between the difference of boundary layer thickness and lifting condensation level and cloud cover.Through further analysis of these three indicators,the sensitivity of different parameterization schemes of CWRF and the influence mechanism of land surface flux on the lifting condensation level.The main conclusions are as follows:(1)Most of the CWRF ensemble members are more accurate in simulating the early morning precipitation peak in North China.However,the simulation results of some members in the afternoon precipitation peak are not ideal,and the precipitation efficiency of the afternoon precipitation event has dropped sharply.The cumulus convective parameterization scheme and the radiation parameterization scheme have the most obvious impact on the diurnal variation of precipitation in North China.(2)Select the correlation between latent heat and soil moisture,the correlation between latent heat and lifting condensation level,and the correlation between the difference between boundary layer thickness and lifting condensation level and cloud cover,which are three indicators to measure land-atmosphere coupling.The positive correlation between latent heat and soil moisture can reflect the control of latent heat on the land surface.The performance of latent heat and lifting condensation level is different under different soil moisture states.The difference between the boundary layer and the lifting condensation level and the cloud cover more reflects the boundary layer convection.However,its connection with the land surface still needs further analysis.(3)The climatic state simulated by the model will eventually affect the land-atmosphere coupling.The cumulus convective parameterization scheme will affect the land-atmosphere interaction by affecting precipitation;the boundary layer scheme will adjust the development of the boundary layer and affect convection and cloud cover;the radiation scheme will pass Adjust the energy reaching the surface to adjust the distribution of surface energy,which in turn affects the land-atmosphere interaction.The land surface scheme will directly change the state of the land surface and thus affect the land-atmosphere interaction.The change of the parameterization scheme will cause differences in the climatic state of the simulated area,resulting in differences in the simulation between variables,which will affect the land-atmosphere interaction.At the same time,the negative latent heat-lifting condensation height correlation may indicate the possible influence of latent heat on the lifting condensation level height.