Quantifying Activation of Aerosol Particles with LES-driven Parcel Simulations

LAURA FIERCE, Jesse Andersen, Will Cantrell, Jerome Fast, Claudio Mazzoleni, Mikhail Ovchinnikov, Raymond Shaw, Fan Yang, Pacific Northwest National Laboratory

     Abstract Number: 432
     Working Group: Aerosols, Clouds and Climate

Abstract
Droplet activation and growth by aerosol particles is an important process governing aerosol-cloud interactions, but modeling the evolution of complex particle populations within a cloud's turbulent environment is computationally difficult. Modeling studies of cloud condensation nuclei activity by complex aerosol populations have typically relied on idealized parcel simulations in which all particles experience the same environmental properties; turbulence-induced fluctuations in environmental properties are ignored. Here we present a new framework for modeling the evolution of complex particle populations within turbulent clouds. We used high-resolution Large Eddy Simulations of the turbulent environment in the Pi Chamber, a convective cloud chamber at Michigan Technological University, to drive particle-resovled simulations of aerosol-cloud interactions along Lagrangian trajectories within the chamber. The air parcels were initialized with particles sampled from populations simulated by the particle-resovled aerosol model, PartMC-MOSAIC. We show that droplet activation and growth is strongly enhanced by turbulent fluctuations in water vapor and temperature, which indicates that sub-grid heterogeneity in environmental properties must be well represented in models to accurately predict aerosol interactions clouds.