The Sensitivity of Smoke Aerosol Dispersion to Smoke Injection Height and Source-Strength in Multiple AeroCom Models

Abstract. The near-source and downwind impacts of smoke aerosols depend on both emitted mass and injection height. This study examines aerosol dispersion sensitivity to these factors using four global models from the AeroCom Phase III Biomass Burning Emission and Injection Height (BBEIH) experiment. Each model performed four simulations: (1) BASE, using a common emission inventory with default injection height; (2) BBIH, with vertical distribution adjusted using MISR plume heights; (3) BBEM, with an alternative emission inventory; and (4) NOBB, excluding biomass burning emissions. The focus is the April 2008 Siberian wildfire event. Aerosol optical depth (AOD) varied across models. The BASE model median is 27 % higher than the satellite median over the Siberian wildfire source region but is 37 % lower over the western North Pacific, indicating inadequate long-range transport or overly rapid aerosol removal in all models. Near the source, all models overestimate aerosol extinction below 2 km, suggesting injection heights were too low. The MISR plume heights slightly improved simulations, but downwind AOD remained largely underestimated. In BBEM, increased emissions in the models enhanced AOD near the source but did not improve AOD vertical structure there or downwind. Notably, CALIOP detected aerosol layers above 6 km from the source to downwind regions – features absent in all model simulations. These findings suggest that increasing emission strength alone is insufficient; improving vertical injection near-source to loft more smoke above 3 km in Siberia and reducing excessive aerosol wet removal during transport are critical.