Impact of modified turbulent diffusion of PM<sub>2.5</sub> aerosol in WRF-Chem simulations in eastern China

Abstract. Correct description of the boundary layer mixing process particle is an important prerequisite for understanding formation mechanism pollutants, especially during heavy pollution episodes. Turbulent vertical determines distribution momentum, heat, water vapor and pollutants within planetary (PBL). However, what questionable that turbulent particles usually denoted by diffusion heat in Weather Research Forecasting model coupled with Chemistry (WRF-Chem). With mixing-length theory, relationship established, embedded into WRF-Chem verified based on long-term simulations from 2013 to 2017. The new coefficient used represent separately, without deteriorating simulation results meteorological parameters. improves pollutant concentration varying degrees, simulated PM2.5 are improved 8.3 % (2013), 17 (2014), 11 (2015) 11.7 (2017) eastern China, respectively. Furthermore, expected increase due reduction mountainous areas, but did not change as expected. Therefore, under influence complex topography, insensitive concentration. For evolution more susceptible advection transport because obvious wind speed gradient gradient. In addition concentration, CO a primary has also been improved, which shows extremely critical variation various aerosol pollutants. Additional joint research other processes (e.g., dry deposition, chemical emission processes) may be necessary promote development future.