Abstract for presentation at 14th IUAPPA World Congress

Both meteorological and geological conditions are two important factors affecting ambient air quality. Taiwan Island is surrounded by oceans but the local circulation on the island is generally complex. The Central Mountain (about 2000 meter high) penetrates the island from north to south. The slope of east side of the mountain is much sharper than that to the western side, producing a suitable geographic condition for forming subsidence inversion on west sides of the mountain as winds coming from the east. This study aimed to investigate an air pollution episode case in southern Taiwan associated with ozone accumulated in the ambient air of confined area. The relationships between local circulation and accumulation of ozone were investigated. The experimental results indicate a local circulation formed on west side of the mountains while the wind system blew southwesterly at daytime but turned to northwesterly at night. For determining the formation of local circulation in the atmosphere, the vertical structure of the atmosphere was reestablished by collecting vertical meteorological information through intensive observations with sounding and pible in this study. Investigation results show that the ozone concentration reached maximum high around mid-noon and afternoon and the high-ozone area was confined at the place where low pressure circulation was generated. The field results also indicated that the diurnal variation in wind and temperature was significant. The relation is closely between the distribution of ozone concentration and the formation of low pressure circulation. The weak wind and fare weather was favored for poor air quality.