Improving Wet and Dry Deposition of Aerosols in WRF?Chem: Updates to Below?Cloud Scavenging and Coarse?Particle Dry Deposition

Wet and dry depositions of aerosols in WRF-Chem are revisited updated based on recent observational findings. Traditionally, in-cloud scavenging was thought to play a more dominant role aerosol wet removal than below-cloud scavenging. However, field measurements indicated considerable contribution 50%–60% total deposition. In contrast, the simulated previous version too large, exhibiting 88%–95%, likely due binary representation cloud fraction. To reduce model bias, this study adopts continuous-type fraction implements semi-empirical parameterization. Simulation results with new scheme show that (in-cloud) is increased 63%–66% (decreased 34%–37%), well capturing estimates. The magnitude deposition by 18.2% for SO4, 7.16% NO3, 14.8% NH4, showing better agreements observations particularly SO4 NH4 reduces so reproduces surface PM2.5 PM10 concentrations, which also partly attributed It found velocity high coarse mode particles when friction underestimates concentration. constrained effectively improves performance reducing particles.