Roles of Chemistry, Microphysics and Transport in Wet Removal of Soluble Species in the DC3 Oklahoma May 29, 2012 Severe Storm

In deep convective storms, wet scavenging of soluble species, as well as aqueous- and ice-phase chemistry, affects the net transport of soluble O3 and aerosol precursors to the upper troposphere (UT), and thus impacts air quality and climate. This study examines wet removal of soluble trace gases in the severe storm cluster observed in Oklahoma on May 29, 2012 during the 2012 DC3 (Deep Convective Clouds and Chemistry) field campaign. WRF-Chem simulations are conducted at cloud resolving scales (dx <= 1km), using the MOSAIC bin aerosol scheme, aqueous chemistry, and wet removal in liquid and frozen hydrometeors. A new capability to specify the fraction of each species that is retained in ice upon hydrometeor freezing is added, and sensitivity simulations are compared with observations to determine the best estimate of the retention factor for each species. Furthermore, tracking of solute in individual liquid and frozen hydrometeor classes is implemented in WRF-Chem based on Barth et al. (JGR, 2001). Scavenging efficiencies are calculated from the model and observations using a multi-component mixture model, which includes entrainment of free and upper tropospheric air. The simulations are compared with in-situ trace gas and aerosol observations and ground-based radar wind and hydrometeor fields in order to assess the relative impact of aqueous chemistry, photochemistry, and microphysical transport on the scavenging efficiencies for different species.