Oral or Poster

IAMAS

M01 - Atmospheric Chemistry in the Anthropocene: From the Urban to Global Scales

Temporal variations of carbonaceous aerosols at Anmyeon-do Global Atmosphere Watch station in relation to wildfires occurrence

Recent climate change driven by human greenhouse gas emissions is increasing temperatures, accelerating droughts, and altering precipitation patterns. Wildfires are uncontrolled combustion processes that occur in natural landscapes such as forests, grasslands, or meadows, and the frequency and intensity of wildfires are expected to rise with climate change. Wildfires release various gases and aerosol components into the atmosphere. Among them, light-absorbing aerosols, including black carbon (with a positive radiative forcing of +0.11 [-0.20 to 0.42] W m-2), are emitted in large amounts, impacting air quality and contributing to climate change. This study analyzes the long-term trend of carbonaceous aerosol concentrations from 2017 to 2023 at the Anmyeon-do Global Atmosphere Watch station, one of the background areas in South Korea. The goal is to estimate the long-term impact of wildfires occurring throughout South Korea on background concentrations and examine their relationship with climate change. The annual mass concentrations of equivalent black carbon (eBC), measured by an Aethalometer (AE31, Magee Scientific), ranged from 0.70 to 1.11 ug STPm-3 from 2017 to 2023, with the highest value recorded in 2020. The contribution of eBC showed a slight upward trend (0.0025 ug STPm?3 year-1). In particular, 756 wildfires occurred in 2022, with a burned area of approximately 25,000 hectares. The annual average eBC concentration for that year was 0.99 ug STPm-3, higher than the overall period average of 0.90 ug STPm-3. The contribution of vegetation combustion calculated using the absorption Angstrom exponent (AAE) ranged from 24% to 30% annually, with higher values observed in 2019 and 2022. Between 2017 and 2023, a total of 4,162 wildfires occurred. The frequency of wildfires in March and April (23% and 22%, respectively) and the burned area (59% and 27%) were significant, with the monthly average relative humidity being about 60%, relatively low. The eBC mass concentrations and wavelength-dependent absorption coefficients in March and April showed a proportional relationship with the number of wildfires, but no correlation with the burned area was observed. The contribution of vegetation combustion showed a slight relationship with wildfire frequency, and was more strongly correlated with the annual trends in March than with the annual average data. A detailed analysis of the relationship between wildfire occurrences on the Korean Peninsula and the concentrations of carbonaceous aerosols measured at the Anmyeon-do Global Atmosphere Watch station will be conducted. Using carbonaceous aerosol data observed in background areas to assess the impact of wildfires is expected to help estimate the effects of climate change and assist in policy formulation. Acknowledgments This material was produced with the support of the Korea Meteorological Administration National Institute of Meteorological Sciences' "Development of Dust and Haze Monitoring and Forecasting Technology (KMA2018-00521)" and was conducted with funding from the government (Ministry of Science and ICT) and supported by the National Research Foundation of Korea (NRF-2021R1C1C2011543 & RS-2023-00218203).