Forest fire smoke long-distance transport track analysis and its impacts on air quality

The forest fires, which occur around the world each year, have had a great influence on air quality. It is difficult to research the pollutant contribution of forest fire smoke longdistance transport to the ambient environment. This study attempted to use numerical models to investigate the possible air quality effect of Great Xing´ anling forest fire smoke on other regions from 28 July to 18 August in 2002. The meteorological model MM5 (Fifth-Generation NCAR / Penn State Mesoscale Model) was used to analyze the synoptic pattern during the fire episode and supply the track analysis model with meteorological field. MM5 was configured with domain covering China of 105-135°E, 35-60°N, with horizontal grid spacing of 30km. Twenty four full σ levels extend from surface to the model top of 200 hpa. It was found that there was a long-term stationary high pressure system controlling most regions of North China during 5-14 Aug, which was conductive to the storage of air pollutants and made it keep a relatively high concentration during the slowly longdistance transport. Besides, the Hybrid Single-Particle Langrangian Integrated Trajectory model version 4 (HYSPLIT_4) was used in forwards mode to make a research on the possible affected regions of the forest fire pollutants. The horizontal track analysis results indicated that regions of north Inner Mongolia were all affected by the fire smoke. The comparison between vertical track analysis and ground observations of PM10 concentration in Beijing suggested that the heavily polluted PM10 released from the forest fire may had made certain contributions to the high PM10 level in Beijing during this period. The methodology of forest fire smoke longdistance transport track analysis based on MM5 and HYSPLIT_4 makes three-dimensional forest fire transport analysis come true, and it would be helpful to analyze the transport path of smoke in sudden fire accidents.