Repository logo

TOMAS-VBS model for "More than emissions and chemistry: fire size, dilution, and background aerosol also greatly influence near-field biomass burning aerosol aging"




Hodshire, Anna
Pierce, Jeffrey
Bian, Qijing

Journal Title

Journal ISSN

Volume Title


Biomass burning emits particles (black carbon and primary organic aerosol; POA) and precursor vapors to the atmosphere that chemically and physically age in the atmosphere. This theoretical study explores the relationships between fire size (determining the initial plume width and concentration), dilution rate, and entrainment of background aerosol on particle coagulation, OA evaporation, and secondary organic aerosol (SOA) condensation in smoke plumes. We examine the impacts of these processes on aged smoke OA mass, geometric mean diameter (Dg), peak lognormal modal width (σg), particle extinction (E), and cloud condensation nuclei (CCN) concentrations. In our simulations, aging OA mass is controlled by competition between OA evaporation and SOA condensation. Large, slowly diluting plumes evaporate little in our base set of simulations, which may allow for net increases in mass, E, CCN, and Dg from SOA condensation. Smaller, quickly diluting fire plumes lead to faster evaporation, which favors decreases in mass, E, CCN, and Dg. However, the SOA fraction of the smoke OA increases more rapidly in smaller fires due to faster POA evaporation leading to more SOA precursors. Net mass changes for smaller fires depend on background OA concentrations; increasing background aerosol concentrations decrease evaporation rates. Although coagulation does not change mass, it can decrease the number of particles in large/slowly diluting plumes, increasing Dg and E, and decreasing σg. While our conclusions are limited by being a theoretical study, we hope they help motivate future smoke-plume analyses to consider the effects of fire size, meteorology, and background OA concentrations.


This dataset provides all of the FORTRAN and python code needed to run the model as described in the above publication. Users will need to have access to a FORTRAN compiler. This code was run using the gfortran compiler.
Department of Atmospheric Science

Rights Access


aerosol microphysics
smoke aging
smoke modeling


Associated Publications

Hodshire, A. L., Bian, Q., Ramnarine,E., Lonsdale, C. R., Alvarado, M. J.,Kreidenweis, S. M., et al. (2019). More than emissions and chemistry: Fire size,dilution, and background aerosol also greatly influence near‐field biomass burning aerosol aging. Journal of Geophysical Research: Atmospheres,124, 5589–5611.
Bian, Q., Jathar, S. H., Kodros, J. K., Barsanti, K. C., Hatch, L. E., May, A. A., et al. (2017). Secondary organic aerosol formation in biomass-burning plumes: Theoretical analysis of lab studies and ambient plumes. Atmospheric Chemistry and Physics, 17(8), 5459–5475.