연안 대도시 해풍 풍하측 계곡지역의 지표오존 분포 특성: 계절변화와 바람과의 관계

The seasonal variations of ozone (O3) concentrations were investigated with regard to the relationship between O3 and wind distributions at two different sites (Jung Ang (JA): a semi-closed topography and Seo Chang (SC): a closed topography) within a valley city (Yangsan) and their comparison between these sites (JA and SC) and two non-valley sites (Dae Jeo (DJ) and Sang Nam (SN)) located downwind from coastal cities (Busan and Ulsan). This analysis was performed using the data sets of hourly O3 concentrations, meteorological factors (especially, wind speed and direction), and those on high O3 days exceeding the 8-h standard (60 ppb) during 2008-2009. In summer and fall (especially in June and October), the monthly mean values of the daily maximum O3 concentrations and the number of high O3 days at JA (and SC) were relatively higher than those at DJ (and SN). The increase in daytime O3 concentrations at JA in June was likely to be primarily impacted by the transport of O3 and its precursors from the coastal emission sources in Busan along the dominant southwesterly winds (about 5 m/s) under the penetration of sea breeze condition, compared to other months and sites. Such a phenomenon at SC in October was likely to be mainly caused by the accumulation of O3 and its precursors due to the relatively weak winds under the localized stagnant weather condition rather than the contribution of regional transport from the emission sources in Busan and Ulsan.