Numerical Simulations of Heavy Fog Processes on Expressways Based on Different Parameterization Schemes
In order to compare different effects on simulations of heavy fog processes under various microphysics， planetary boundary layer and land surface schemes， 21 heavy fog events selected from the observation data of expressway weather monitoring system from 2011 to 2013 were simulated using WRF (Weather Research and Forecasting Model). Influence of different parameterization schemes on simulating these fog events was discussed and the forecasting indexes of fog formation based on the output physical variables of WRF were determined. The results are as follows： （1） The simulation of the whole fog occurring processes is the best when selecting WDM6 scheme as the microphysics scheme， QNSE scheme as the planetary boundary layer scheme and the SLAB scheme as the land surface scheme considering the effects of different parameterization schemes in simulating the nearsurface meteorological factors， the air temperature in the upperlevel atmosphere and the distribution of fog areas comprehensively. （2） Under the optimum configure of the parameterization schemes and giving consideration to the limited computing resources of the meteorological professional departments in China and the suitable vertical resolution of the model，the analysis on the numerical simulation results of atmospheric backgrounds during the 21 heavy fog events demonstrates that the forecasting indexes of heavy fog on the expressway of Jiangsu Province are that liquid water content at lowest model level (30-40 m) is more than 0.015 g·kg-1， or 2 m relative humidity is more than 95% and 10 m wind speed is less than 3 m·s-1 at the same time.