An integrated air quality modeling system coupling regional-urban and street models in Beijing
Wang Tao, Jie Li, Jinxiu Pan, Dongsheng Ji, Youngseob Kim, Luolin Wu, Xuemei Wang, Xiaole Pan, Yele Sun, Zifa Wang, Wenyi Yang, Huiyun Du
Abstract
Recently, ozone (O3) pollution has become a significant problem for Beijing owing to its high traffic volume. To improve the simulation of street-scale nitrogen oxides (NOx) and O3, an integrated air quality modeling system coupling regional urban/street (IAQMS-street) was developed for Beijing. A weather research and forecasting atmospheric model, regional nested air quality prediction system, model of urban network of intersection canyons and highways, and a real-time on-road emission model were coupled by a downscaling method. A two-week simulation with high O3 concentrations (September 25, 2020 to October 8, 2020) was conducted to evaluate the impact of high-resolution traffic emissions and the street-scale simulation by three sensitivity scenarios. The results showed that IAQMS-street improved the model performance for NO, NO2, and O3 compared to regional models. The correlation coefficients (R) and normal mean bias (NMB) increased from ~0.3 to ~0.6 and from −83.3% to 14.8% for NO, respectively. For O3, the R increased by ~10%, and the NMB decreased from 48.7% to −4.4%. In particular, the model performance for O3, NO, and NO2 in high-concentration periods was significantly improved by IAQMS-street. Both high-resolution vehicle emissions and street-scale simulations contributed to this improvement. Our results showed that IAQMS-street provides a more realistic tool for simulating and resolving finer urban photochemical pollution heterogeneity in Beijing.