Understanding emissions and chemistry in Asia by reconciling the regional chemical transport model results with the observations from satellites, aircrafts, ship, and surface monitors

Asia has experienced an unprecedented and rapid economic growth in the last decades, which has resulted in severe local and global air quality issues. The air quality in this region is not only affected by anthropogenic sources, but also by natural sources such as dust and vegetation. Current understanding of the complicated interplay between the emissions and chemistry in this area is quite limited. An International Cooperative Air Quality Field Study in Korea (KORUS-AQ) in 2016 along with routine observations from satellites and surface monitors provides a unique opportunity to explore the emissions and photochemistry in continental Asia and South Korea. In this study, we use the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate multiple photochemical pollution cases during the KORUS-AQ campaign. By comparing the model results with the aircraft, ship, and ground-based observational data collected during the campaign, we are able to assess the current understanding of the emissions and chemistry relevant to the tropospheric ozone and aerosols of this region. Additionally, top-down NO_x emissions estimations based on the analysis of satellite NO₂ retrievals for multiple years in pollution hot spots over China and South Korea are integrated into our KORUS-AQ modeling system to better predict atmospheric composition in this region. Finally, our modeling approach clarifies the contribution of local and regional sources to the air quality in the Korean Peninsula.