Characteristics of Haze Episodes during Winter in Seoul, Korea 2021 Using an Aerosol Mass Spectrometer

KYUNG HWAN KIM, Su-Yeon Choi, Junwon Ko, Myeong Ha Lee, Hyoun Cher Jin, Seung-Bok Lee, Jin-young Kim, Gwi-Nam Bae, Korea Institute of Science and Technology

     Abstract Number: 235
     Working Group: Urban Aerosols

Abstract
We investigated three haze episodes out of five episodes occurred in the Seoul Metropolitan Area (SMA) during December in 2021 to understand how the haze in the SMA occurs and it ends. Both gaseous and particulate matters were measured using on-line instruments system. For the particulate matters, an aerosol mass spectrometer (AMS) was used to see the temporal variations of organic and inorganic components in PM1.0. Among the three episodes, EP1 displayed the highest PM1.0 concentrations reaching almost 80 μg/m3 in PM1.0. On the other hands, EP2 and 3 showed relatively moderate increase reaching 40 to 50 μg/m3 in PM1.0. Interestingly, EP2 and 3 exhibited quite different organic and inorganic compounds increase and decrease tendency reflecting the main trigger of the haze occurrence might be different in the two episodes. The consecutive haze days during EP1 and 2 were ended up by both rainout (4 to 7 mm) and northerly wind with high wind speeds (>5 m/s) while EP3 was only ended up by northerly wind with high wind speeds. In fact, 1 to 2 mm of precipitation may contribute to the elevated inorganic compounds such as nitrate, sulfate, ammonium, and chloride by increasing R.H. reaching almost 100% whereas the organic components were not increased as much as inorganic components were in EP3. In summary, meteorological parameters are the crucial factors to make and end up the haze episodes in SMA during December in 2021.