The Impact of Foreign SO₂ Emissions on Aerosol Direct Radiative Effects in South Korea

• Main Authors: Jung-Woo Yoo, Wonbae Jeon, Hwa Woon Lee, Jeonghyeok Mun, Soon-Hwan Lee, Soon-Young Park
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Atmosphere
• Subjects: SO₂ emissions; SO₄²⁻; WRF–CMAQ two-way coupled model; aerosol direct radiative effects
• Online Access: https://www.mdpi.com/2073-4433/11/9/887

This study examined the impact of foreign SO₂ emission changes on the aerosol direct radiative effects (ADRE) in South Korea. Simulations that applied basic emissions (BASE) and simulations that applied reduced SO₂ emissions from foreign sources (R_FSO2) were performed, respectively, using the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) two-way coupled model. In addition, the difference between the two experimental results was calculated (i.e., R_FSO2 minus BASE) to quantitatively identify the impact of foreign SO₂ emission reduction. The reduction in foreign SO₂ emissions caused a decrease in the concentration of SO₂ flowing in from overseas to South Korea. As a result, a clear decrease in SO₄²⁻ concentration was shown mainly in the southwest coast of South Korea. The difference in PM_2.5 concentration in South Korea according to the foreign SO₂ emission reduction did not correspond to the difference in SO₄²⁻ concentration; it was determined in a complex way by the changes in SO₄²⁻ concentration caused by SO₂ concentration changes, and the subsequent series of changes in NO₃⁻ and NH₄⁺ concentrations. The differences in SO₄²⁻ and PM_2.5 concentrations caused by the foreign SO₂ reduction also affected the ADRE changes in South Korea. The distribution of ADRE difference between the two experiments was not consistent with the distribution of PM_2.5 concentration difference, but it was very similar to the distribution of SO₄²⁻ concentration difference. These results imply that the ADRE of South Korea is not simply proportional to PM_2.5 concentration and may be determined by concentration changes of SO₄²⁻.