The Influence of Dry Deposition on Surface Ozone Simulations Under Different Planetary Boundary Layer Schemes over Eastern China

Dry deposition is an important ozone sink in the planetary boundary layer (PBL), but how it affects ozone levels has not been systematically quantified. Here we investigate the influences of PBL mixing parameterizations on surface ozone and dry deposition in eastern China using a regional air quality model (WRF-Chem) and further quantify the contributions of dry deposition to ozone tendencies both near the surface and in the PBL with the integrated process rates (IPR) analysis. We analyze three PBL schemes coupled with their corresponding surface layer (SFL) schemes, including Yonsei University (YSU), Mellor–Yamada–Janjić (MYJ), and Asymmetric Convective Model v2 (ACM2). The results show that model simulations with different PBL-SFL schemes have differences of 6.5-18.5% for surface ozone concentration and 3.6-15.3% for ozone dry deposition over populous regions of eastern China. IPR analyses with YSU_MM5 show that ozone dry deposition accounts for 47-100% of hourly surface ozone losses and 18-100% of hourly PBL ozone losses. Model sensitivity simulations by suppressing ozone dry deposition would enhance surface ozone in eastern China by 24-30% (20.6-35.7 μg m^-3) during the daytime and 61-82% (26.0-46.1 μg m^-3) at night. The dry deposition process significantly promotes downward vertical mixing to the surface layer, compensating for the surface loss by dry deposition, thus explaining the smaller contribution estimates by the sensitivity approach than IPR analyses. We further show that different meteorological conditions simulated by different PBL-SFL schemes affect daily ozone simulations not only through the chemistry process as previously recognized but also considerably by the dry deposition process.