10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Physical and Chemical Submicron Aerosols Properties and Their Link to Size-resolved Aerosol Hygroscopicity in Summer/Spring of Seoul, Korea
NAJIN KIM, Minsu Park, Seong Soo Yum, Hye Jung Shin, Jong Sung Park, Joon Young Ahn, Yonsei University
Abstract Number: 1046 Working Group: Aerosol Chemistry
Abstract Hygroscopic behavior of aerosols are important parameter of climate change and air quality as aerosol hygroscopicity is not only connected to cloud condensation nuclei (CCN) activity but also to the visibility in highly polluted areas. It is widely known that aerosol hygroscopicity is closely related to physical and chemical properties of aerosols. In this study, characteristics of submicron aerosols and their links to aerosol hygroscopicity are examined based on the results of KORUS-AQ (May-June, 2016) and MAPS-Seoul (May-June, 2015) campaigns, which aims at understanding various aspects of air quality problem in Seoul, highly urbanized area in Korea. Size-resolved aerosol hygroscopicity were measured by hygroscopic tandem differential mobility analyzer (HTDMA) and analyzed with data from various instruments for measuring physical and chemical aerosol properties: CPC, SMPS, CCNC, HR-ToF-AMS and MAPP.
Distinct diurnal patterns of size-resolved aerosol hygroscopictiy and mixing state were observed during the measurement periods. In the morning, aerosols are externally mixed with freshly emitted particles by vehicles and existing aged aerosols. Mixing state change occurred in the afternoon when photochemical process is active. Sharply increased hygroscopicity of small particles and O/C ratio were observed in that time. During KORUS-AQ campaign, chemical composition of aerosols varied by sources (inorganic-dominant/ organic-dominant period) and impacted on aerosols hygroscopicity and even CCN spectrum even though aerosol number concentration changed very little. Good agreement with GF-derived κ from HTDMA and AMS-based κ when considering oxidation state and BC mass concentration also implies that hygroscopic properties of aerosols are associated with chemical properties of aerosols as well as physical properties of aerosols. Analysis of aerosol chemical composition with size-resolved aerosol hygroscopicity during NPF events and difference between GF-derived κ and CCN-derived κ will be discussed in the conference.