Development of WRF/CUACE v1.0 model and its preliminary application in simulating air quality in China

Abstract. The development of chemical transport models with advanced physics and chemical schemes could improve air-quality forecasts. In this study, the China Meteorological Administration Unified Atmospheric Chemistry Environment (CUACE) model, a comprehensive chemistry module incorporating gaseous chemistry and a size-segregated multicomponent aerosol algorithm, was coupled to the Weather Research and Forecasting (WRF)-Chem framework using an interface procedure to build the WRF/CUACE v1.0 model. The latest version of CUACE includes an updated aerosol dry deposition scheme and the introduction of heterogeneous chemical reactions on aerosol surfaces. We evaluated the WRF/CUACE v1.0 model by simulating PM_2.5, O₃, and NO₂ concentrations for January, April, July, and October (representing winter, spring, summer, and autumn, respectively) in 2013, 2015, and 2017 and comparing them with ground-based observations. Secondary inorganic aerosol simulations were also evaluated through a simulation of a heavy haze pollution event during 9–15 January 2019 in the North China Plain. The model well captured the variations of PM_2.5, O₃, and NO₂ concentrations in all seasons in eastern China. However, it is difficult to accurately reproduce the variations of air pollutants over Sichuan Basin, due to its deep basin terrain. The sulfate and nitrate simulations are substantially improved by introducing heterogenous chemical reactions into the CUACE model (change in bias from −95.0 % to 4.1 % for sulfate and from 124.1 % to 96.0 % for nitrate). The development of the WRF/CUACE v1.0 model represents an important step towards improving air-quality modelling and forecasts in China.