Abstract for presentation at 14th IUAPPA World Congress

Taiwan is a subtropical island. Since the coast zone of Taiwan has the highest density of population and is the major industrial area, the role of local circulation in the transporting and diffusing of atmospheric pollutants should be very important. A nested regional-scale air quality modeling system was applied in this study to explore the episode of high ozone concentration level occurred in central Taiwan in April 2004. The studied episode was divided into 3 periods. In the first period, Taiwan was situated in the warm side of the front, causing some precipitation in this area and resulting low ozone concentration level. In the second period, the stationary high pressure covered Taiwan island. The atmosphere was very stable and the pollutants was easily accumulated and caused the high ozone concentration. In the third period, the high-pressure system moved eastward and made the wind speed a little higher. The ozone concentration is a little less than the first period.
The contribution of long-range transported ozone to central Taiwan is about 40% while that of NO_x and NMHC is minor. The contributions due to long-range transported CO and SO_x are 25% and 30%, respectively. As for Puli station, the most inland EPA monitoring station in central Taiwan, the contributions of long-range transported ozone, CO, and Sox were about 28%, 22%, and 45%, respective, while that of NO_x and NMHC were still minor. We concluded that the contribution percentage of long-range transport air pollutants were dependent on their life-times.