도시 및 배경지역의 에어로졸 화학성분별 광학특성과 직접적 복사강제력 추정 연구

Abstract

In this study, the characteristics of time and spatial concentration according to four aerosol chemical components (Water-soluble, Insoluble, BC and Sea-salt) were compared and analyzed in urban (Seoul, Daejeon, and Busan 4 sites) and background (Jeju Aewol and Gosan) areas during each study period. Due to the limitations of data collection, each site used different PM2.5 data for this study. Busan, Daejeon, and Jeju Gosan sites used daily aerosol sampling data and Seoul and Jeju Aewol sites used hourly aerosol sampling data. The optical properties (e.g. absorption, scattering, and Aerosol Optical Depth (AOD)) of the four different aerosol chemical components were analyzed using the OPAC model and direct radiative forcing using the SBDART model at each study site. Also concentration, AOD, DRFSFC, and DRFTOA of each aerosol component at the six different study sites (Busan 4 sites, Daejeon and Jeju Aewol) were calculated during haze and non-event periods. Overall, the highest concentration of Water-soluble aerosol component was followed by Insoluble, BC or Sea-salt. In general, the concentration of aerosol components in urban environments (e.g. Seoul and Busan) where the effects of artificial emission sources was high due to population density and many vehicles. And the sea-salt components did not show significant differences between regions. Comparing the common year (2013∼2014) of the urban area (Busan Yeonsan) and the background area (Jeju Gosan), the water-soluble component was much higher in urban area, but sea-salt component was about 1.2 times higher in Jeju Gosan. This is thought to be due to the geographic and topographical features of Jeju Island as it is surrounded by four sides of the sea. The diurnal variation of component concentration in Seoul Gwangjin and Jeju Aewol sites, due to the photochemical reaction in the afternoon, the aerosol concentration was high at noon and in the afternoon time (12:00 to 16:00). Regional aerosol optical characteristics, the optical parameters (AOD, absorption coefficient, dissipation coefficient, etc.) in urban areas were high, similar to the concentration patterns of chemical components. Furthermore, the BC component had the highest absorption coefficient value despite its relatively small concentration due to the strong light absorption ability. The diurnal variation was mainly the highest at 8:00 to 9:00, and showed a tendency to decrease unlike the concentration pattern in the afternoon. This is presumably because the relative humidity in the afternoon is lower than in the morning. During the study, total DRF by eaerosol chemical component of every study site was common to high negative radiative forcing of water-soluble components, followed by BC (positive DRF in TOA), Insoluble, and Sea-salt components. Negative DRFSFC was generally high from late fall to early spring, showing a pattern similar to AOD values as a whole. In the case of DRFTOA, it was generally estimated to be the similar order of radiative forcing with SFC (water-soluble, BC (positive DRF), sea-salt and insoluble components). The daily variation of DRF was higher in the noon or afternoon compared to the early morning, due to the increase in photochemical reaction. In the case of the Aewol site BC component, the average DRF in the TOA was estimated at an average of about +7.7 W/m2 from 11:00 to 15:00 hours. Overall, the aerosol concentration of haze was higher than that of non-haze event, especially in the order of the Jeju Aewol and the Busan Gwangbok and the Daejeon Yuseong (39.7 μg/m3 and 33.3 μg/m3 , respectively). The AOD optical characteristics were also shown to be similar to the concentration. The DRF on haze days was the highest among the sites, with DRFSFC and DRFTOA of water-soluble component at Busan Gwangbok at 1.9 times and 1.8 times, respectively, compared to non-haze days.