A sensitivity study of ozone entrainment flux on boundary layer micrometeorology fields

Previous studies have proved that the impact of high ozone amounts in the residual layer can account for up to 80% of the ozone maxima in the following day. This high ozone in the residual layer mixes into to the Planetary Boundary Layer (PBL) through the entrainment processes as the growth of PBL occurs in the morning. Conversely, anthropogenic pollutants emitted from the surface mix into the Free Troposphere (FT) and are transported to other places. Therefore, entrainment flux is one of the important connections between the local-scale/urban-scale and the regional scale. Ozone entrainment flux is defined as the product of the entrainment velocity and the ozone gradient between the PBL and the FT over the unit length. Many micrometeorological parameters, including the horizontal wind, buoyancy flux, virtual potential temperature, etc., determine the ozone entrainment flux by determining the ozone gradient and the entrainment flux. We will present a sensitivity study of the dependence of ozone entrainment flux on the ozone gradient, surface heat flux, buoyancy flux, and horizontal wind using Dutch Large Eddy Simulation (DALES) model. Understanding the ozone entrainment flux will help improve air-quality model prediction and simulation and bridge the gap between the lowermost altitude of ozone satellite retrieval and surface ozone concentration.