AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Simulating Black Carbon Mixing State in the Planetary Boundary Layer with a Particle-Resolving Single-Column Model
JEFFREY H. CURTIS, Nicole Riemer, Matthew West, University of Illinois at Urbana-Champaign
Abstract Number: 412 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract The chemical reactivity, cloud condensation nuclei activity, radiative properties and health impacts of black-carbon-containing particles depend crucially on the aerosol mixing state. The recently developed particle-resolving aerosol box model PartMC-MOSAIC has allowed unique insight into the evolution of aerosol mixing state as it tracks per-particle evolution for an aerosol population undergoing coagulation, condensation, dilution and emission in a Lagrangian air parcel. However, so far, spatial resolution was lacking.
Here we present a new model, PartMC-1D, which couples the aerosol box model PartMC-MOSAIC with the single-column version of the Weather Research and Forecast (WRF) model. The resulting spatially resolved model predicts the per-particle size and composition as well as transport processes driven by local meteorology to provide detail on the evolution of the aerosol mixing state as the planetary boundary layer develops during the day.
In this presentation we first explain the newly developed, particle-based stochastic algorithm for turbulent diffusion, and show results of code verification. We then present spatially- and particle-resolved simulation results of black carbon aging in a polluted boundary layer. These results indicate that while the bulk concentration of black carbon is well-mixed in the boundary layer during the day, there is a strong dependence of black carbon mixing state on height with fresh black carbon particles existing in only the lowest layers. Based on these results we quantify the implications for cloud condensation nucleation activity and optical properties of black-carbon-containing particles.