27ATCHEM Investigating the Impacts of Wet Scavenging on Tropospheric Aerosols during ACTIVATE using FLEXPART Air Mass History and GEOS-Chem Simulations

Wet scavenging is the dominant loss process for tropospheric aerosols. Aerosol removal and chemical evolution in different cloud (liquid, mixed-phase, and ice clouds) and precipitation (rain and snow) regimes can vary substantially. The role of wet scavenging in reforming aerosol mass, composition, and vertical distribution can be better determined by building a statistical relationship between a large number of airborne aerosol measurements and cloud and precipitation regimes experienced during the air mass transport history. This work investigates the impacts of wet scavenging on tropospheric aerosols using aircraft measurements of aerosols during ACTIVATE in conjunction with FLEXPART air mass history and GEOS-Chem chemical transport model simulations of aerosols and radionuclide tracer Pb-210. ACTIVATE is a NASA Earth-Venture Suborbital-3 mission to robustly characterize aerosol-cloud-meteorology interactions over the Western North Atlantic Ocean during late winter to early summer using extensive in situ and remote sensing airborne measurements. The mission provides a rich dataset for aerosols affected by clouds and precipitation over North America and the Western North Atlantic Ocean. We classify and characterize aerosol composition measurements during ACTIVATE based on simulated air mass transport history indicators, including transport pathways, aerosol production and loss rates, and accumulated precipitation during transport (APT). These indicators facilitate the characterization of aerosols affected by certain scavenging processes and the understanding of aerosol composition changes during transport, allowing a better assessment of overall model biases in below-cloud and in-cloud scavenging processes.