Prediction of Heavy Radiation Fog in Nanjing-Zhenjiang Area Along Shanghai-Nanjing Expressway

On the basis of the real-time observation data of 37 days´ heavy radiation fog from 2006 to 2009, taken from 9 stations along Maqun-Douzhuang of Ningzhen Hill Area, a part of Shanghai-Nanjing Expressway, radiation fog forecasting experiments were carried out in this study. The results are as follows: (1) According to the practical need of the Highway Administration, the visibility is divided into three levels:200-500 m, 50-200 m, <; 50 m. When T_diff ≤ -3°C, the heavy radiation fog with visibility less than 50 m may occur before dawn with high possibility, while when T_diff = 4 °C , the minimum visibility will be larger than 500 m; (2) The precipitation provides the major vapor source for the heavy radiation fog occurred, which can not come into being without the precipitation of yesterday and the day before yesterday; (3) The predicting significance of the relative humidity of 2 meters above the ground and 10 m wind, as predicted in the GFS mode.