Influence Of Different Radiation And Underlying Surface Parameterization Schemes On The Numerical Simulation Of Fog Processes

In order to compare the influence of different long and short wave radiation parameterization schemes on the simulation effect of fog formation in WRF model and analyze the impact of different types of surface on the fog formation process,in this thesis,two typical radiation fog processes occurred in Jiangsu during the winter and the spring in 2015 was selected.The different radiation parameterization schemes and surface sensitivity tests in Nanjing area and Lixia River area were carried out respectively.The simulation results were evaluated by the relevant parameters.This study shall be of great theoretical value to explain the mechanism of fog formation and can provide technical support for the early warning and prediction of the fog in Jiangsu.The main conclusions showed as follows:1.The combination of different long and short wave radiation parameterization schemes in WRF model(the weather research and forecast model)were used to the simulation experiments of fog forming processes in Nanjing area and Lixia River area.The analysis of the simulation results indicated:(1)In the simulation of the thermodynamic and water vapor conditions during the spring and winter heavy fog process,the optimal scheme was the combination of the GFDL Scheme in the long wave schemes and the RRTMG Scheme in the short wave schemes.(2)In the simulation of thermal conditions,the simulation effect of temperature at 2m level was better than the surface temperature.(3)In the simulation of water vapor condition,the simulation effect of relative humidity was better than the dew point temperature at 2m level.(4)In the simulation of dynamic conditions,the optimal radiation parameterization scheme was the combination of the CAM Scheme in the long wave schemes and the FLG Scheme in the short wave schemes.But it was necessary to solve the problem that the fluctuation of the simulated value lag behind the observed value in the simulation of wind speed at 10m level of the radiation fog in winter.(5)For the simulation of fog area,the effect of the combination of the GFDL Scheme in the long wave schemes and the RRTMG Scheme in the short wave schemes was the best but the rate of empty forecast was slightly higher,up to 20%.2.In the surface sensitivity simulation of the fog forming processes occurred in the Lixia River region,the experiments of city,water body and the actual surface types were set up respectively to analyze the impact of different types of surface on the fog formation process.The results displayed:(1)the surface temperature and the temperature at 2m level when the surface in the fog area was a distribution of the local cities were larger than those of other surface types.The diurnal variation was obvious and the dew point temperature,relative humidity and the wind speed at 10m level were smaller than those of other surfaces.(2)The dew temperature,relative humidity and the wind speed at 10m level when the surface in the fog area was a distribution of water body were larger than those of other surfaces.But the diurnal variation was not obvious and the surface temperature and the temperature at 2m level were smaller than those of other types.