A FUMIGATION DIFFUSION MODEL DURING THE MOUNTAIN-VALLEY WIND SHIFT PERIOD

The fumigation during the mountain-valley wind shift has been first identified as a special type of pollutant diffusion using the monitoring measurements of Dukou,Southwest Sichuan,China.Such a phenomenon occurs frequently all year around but summer,particularly in winter months.A new model for the fumigation during the mountain-valley wind shift period is developed that allows satisfactory explanation of the fact.Analyses indicate that the model can more accurately predict not only the high concentration of Pollutants but the time and locality of the occurrence as well.The ground concentration of SO2 during fumigation is several times up to over a decade higher than the daily mean for the whole region,one of the main contamination processes that affect the air quality of the city.The medel analyses provide a basis for more effective prediction of the quality and precaution study against the disaster.