Study on forewarning indexes and forecasting models of the high temperature weathers on the Shanghai-Nanjing Expressway

In this paper,30 typical high temperature weather events were filtered with the real-time data monitored by the automatic meteorological monitoring system on the Shanghai-Nanjing Expressway and these events were simulated by the WRF model.The output from the model was used to draw the graphics uniformly,and the forewarning indexes of the high temperature occurrence on the Shanghai-Nanjing Expressway were extracted after the statistical analysis.Based on this,the forecast models of the high temperature at Meicun Station and Heyang Station on the Shanghai-Nanjing Expressway were established.The results show that:(1) The selective simulations on the high temperature weather events along the Shanghai-Nanjing Expressway by using WRF model were feasible.(2) The numerical forewarning indexes of the high temperature on the Shanghai-Nanjing Expressway were extracted as follows:in the previous day the surface temperature at 14:00 was above 40℃,the latent heat flux on the ground at 14:00 was above 350 W·m-2,the air relative humidity near the ground at 14:00 was below 60%,the sensible heat flux at the surface at 08:00 was negative and its absolute value was above 70 W·m-2,and the horizontal wind speed on ground at 08:00 on the predicted day was below 3 m·s-1.When all the indexes meet the requirements,the high temperature weather above 35 ℃ on the predicted day could be forecasted.(3) The forecasting models of the high temperature weathers at Meicun Station and Heyang Station were established by a multiple linear regression method and it was indicated that the forecast accuracy of the forecasting models was satisfactory.