In this study, the concentrations of ozone were analyzed from both urban residential area (U-RA) and urban roadside (U-RS) sites located in Seoul, Korea for the 11 year duration (1996 to 2006). The ozone concentrations at U-RA (14±8.8 ppb) were 50% higher than U-RS site (9.35±5.9 ppb) in association with the local NO sources. The maximum hourly ozone concentration during the day reached 36.4 ppb at 1600 LST, while the minimum of 6.61 ppb was seen at 0800 LST (U-RA). Evaluation of seasonal trend indicated that high ozone concentrations were observed during summer followed by fall and winter. The monthly mean concentrations at U-RA were higher in June (21 ppb) and lower in December (6.8 ppb), while their counterparts at U-RS were 15.3 and 5.7 ppb, respectively. The annual mean values of O3 tend to sensitively reflect the concentration changes in May through September over a year. Consequently, the trends of ozone are found to be fairly dependent on the photochemical activity. According to this study, the overall ozone trend at U-RA is characterized with a steady rise from 2004, while those fo at U-RS with a constant decrease from 2001. It also suggests that the ozone concentrations tend to vary in relation with a number of parameters including the precursor emissions (NO and NO2) and meteorological factors (turbulent mixing, temperature, and solar radiation).

In this study, the concentrations of ozone were analyzed from both urban residential area (U-RA) and urban roadside (U-RS) sites located in Seoul, Korea for the 11 year duration (1996 to 2006). The ozone concentrations at U-RA (14±8.8 ppb) were 50% higher than U-RS site (9.35±5.9 ppb) in association with the local NO sources. The maximum hourly ozone concentration during the day reached 36.4 ppb at 1600 LST, while the minimum of 6.61 ppb was seen at 0800 LST (U-RA). Evaluation of seasonal trend indicated that high ozone concentrations were observed during summer followed by fall and winter. The monthly mean concentrations at U-RA were higher in June (21 ppb) and lower in December (6.8 ppb), while their counterparts at U-RS were 15.3 and 5.7 ppb, respectively. The annual mean values of O3 tend to sensitively reflect the concentration changes in May through September over a year. Consequently, the trends of ozone are found to be fairly dependent on the photochemical activity. According to this study, the overall ozone trend at U-RA is characterized with a steady rise from 2004, while those fo at U-RS with a constant decrease from 2001. It also suggests that the ozone concentrations tend to vary in relation with a number of parameters including the precursor emissions (NO and NO2) and meteorological factors (turbulent mixing, temperature, and solar radiation).

ozone, urban residential area, urban roadside, trend, photochemical activity