Causes Of Changes In The Pollutants Concentration At The Bright Summit Of Mount Huang:a Numerical Simulation

Using HYSPLIT and WRF-Chem model, the causes of pollutants’ diurnal and interdiurnal variation at Bright Summit of Mt. Huang from June to August2011were studied, specially, a parameter was designed based on the residence time field of backword trajectory and pollutants emission intensity field to study the influence of advective transportaion on interdiurnal variation during the observation period; The potential source distributions of O3, which was assorted into three bins of O3levels were investigated by a modified potential source contribution function (PSCF). The reason why O3concentration in the rainy or foggy days at nighttime was higher than those at daytime at the Bright Summit was discussed by a case modeling using WRF-Chem, whose emission source data was refined in this thesis. The main conclusions are as follows:(1) Advective transport parameters well reproduced the variation of CO and O3concentrations, respectively, indicating that advective transport played great impact on the change of CO and O3at the site. The transport intensities of urban regions surrounding the border of Anhui,Hubei and Jiangxi province account for more than half of total intensities.(2) The potential sources of O3bins (>55×10-9,(30-55)×10-9,<30×10-9) at Bright Summit were mainly attributed to developed industrial zones in North China and Yangtze River Delta, industrial zones in the southwest and south and east China Sea, respectively. There were four advective transport types during the observation period, which were classified into transport from crop residue burning, developed industrial zones, air masses originated from southwest and air masses originated from ocean. The CO/O3concentration ratios (×10-9) of the four transport types were474.47/72.50,221.16/57.71,86.31/30.41and51.67/27.45, respectively.(3) Transport from anthropogenic emissions in the distance resulted in higher O3concentration at nighttime at Bright Summit in the rainy or foggy days. Airflow was divided into surrounding and climbing flow under effect of Mt. Huang, and the climbing flow carry O3to Bright Summit. The higher Froude number, the stronger mountain blocking intensity, and strong blocking would lead to low-level adverse fluid and upstream disturbance. Lee waves appeared with high katabatic winds velocity, and O3also present a fluctuant distribution. Lee waves inclined to the upstream with height led to weak substance exchange above Bright Summt, but this phenomenon had no significant effect to O3concentration at Bright Summit.