When Smoke Goes Up, PM Goes Down: Biomass Burning Plume Injection Height Effects on Observation Agreement, Surface PM2.5, and Radiative Forcing

NICOLE JUNE, Jeffrey R. Pierce, Colorado State University

     Abstract Number: 34
     Working Group: Aerosols Spanning Spatial Scales: Measurement Networks to Models and Satellites

Abstract
Aerosols emitted from biomass burning have important effects on human health and climate both regionally and globally. These impacts may be altered by the plume injection height: a higher plume injection height (PIH) may increase lifetime of the smoke and decrease surface concentrations near the source. We use the global chemical transport model, GEOS-Chem-TOMAS, to examine the impacts of biomass burning plume injection height. We run four different PIH scenarios where all smoke is well-mixed into the boundary layer or smoke is injected following one of three plume injection height scenarios based off of heights in the GFAS emissions inventory. In comparison to observations, we find minor changes in agreement with AERONET and CALIPSO full-column AOD between the different PIH scenarios. In simulations where smoke is allowed to be injected above the boundary layer, there are improvements in agreement with CALIPSO extinction coefficient profiles, particularly in boreal regions. Globally, there is a decrease in surface PM_2.5 with the strongest decreases in biomass burning source regions with increasing PIH, and there is also a decrease in the number of days annually where the majority of surface PM_2.5 at a given location is due to smoke. Due to the increase in lifetime of the biomass burning aerosols with increasing PIHs, there is an increase in the tropospheric mass burden due to biomass burning, which increases the cooling seen in the clear-sky direct radiative effect. However, due to increases in smoke above clouds, the all-sky direct radiative effect has slightly less cooling with increasing PIH. The aerosol indirect effect shows more cooling with increasing PIH with the largest changes in marine stratocumulus regions.