Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published June 17, 2015 | Published + Supplemental Material
Journal Article Open

Investigating the links between ozone and organic aerosol chemistry in a biomass burning plume from a prescribed fire in California chaparral


Within minutes after emission, complex photochemistry in biomass burning smoke plumes can cause large changes in the concentrations of ozone (O_3) and organic aerosol (OA). Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP) to simulate the evolution of O_3 and secondary organic aerosol (SOA) within a young biomass burning smoke plume from the Williams prescribed fire in chaparral, which was sampled over California in November 2009. We demonstrate the use of a method for simultaneously accounting for the impact of the unidentified intermediate volatility, semi-volatile, and extremely low volatility organic compounds (here collectively called "SVOCs") on the formation of OA (using the Volatility Basis Set – VBS) and O_3 (using the concept of mechanistic reactivity). We show that this method can successfully simulate the observations of O_3, OA, NO_x, ethylene (C_2H_4), and OH to within measurement uncertainty using reasonable assumptions about the average chemistry of the unidentified SVOCs. These assumptions were (1) a reaction rate constant with OH of ~ 10^(-11) cm^3 s^(−1); (2) a significant fraction (up to ~ 50 %) of the RO_2 + NO reaction resulted in fragmentation, rather than functionalization, of the parent SVOC; (3) ~ 1.1 molecules of O_3 were formed for every molecule of SVOC that reacted; (4) ~ 60 % of the OH that reacted with the unidentified non-methane organic compounds (NMOC) was regenerated as HO_2; and (5) that ~ 50 % of the NO that reacted with the SVOC peroxy radicals was lost, presumably to organic nitrate formation. Additional evidence for the fragmentation pathway is provided by the observed rate of formation of acetic acid (CH_3COOH), which is consistent with our assumed fragmentation rate. However, the model overestimates peroxyacetyl nitrate (PAN) formation downwind by about 50 %, suggesting the need for further refinements to the chemistry. This method could provide a way for classifying different smoke plume observations in terms of the average chemistry of their SVOCs, and could be used to study how the chemistry of these compounds (and the O_3 and OA they form) varies between plumes.

Additional Information

© 2015 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Received: 8 November 2014 – Published in Atmos. Chem. Phys. Discuss.: 22 December 2014; Revised: 30 April 2015 – Accepted: 25 May 2015 – Published: 17 June 2015. The authors thank the anonymous reviewers and Manish Kumar Shrivastava of Pacific Northwest National Laboratory (PNNL) for their helpful comments. This modeling work was funded by NSF grant number AGS-1144165 to M. J. Alvarado and C. R. Lonsdale of Atmospheric and Environmental Research (AER) and R. J. Yokelson of the University of Montana. Original sampling of the Williams fire was funded primarily by the Strategic Environmental Research and Development Program (SERDP) projects SI-1648 and SI-1649 and partially by NSF grants ATM-0513055 and ATM-0936321. The California Institute of Technology contributions were partially funded through Dreyfus Award EP-11-117 to J. S. Craven.

Attached Files

Published - acp-15-6667-2015.pdf

Supplemental Material - acp-15-6667-2015-supplement.zip


Files (1.3 MB)
Name Size Download all
221.7 kB Preview Download
1.1 MB Preview Download

Additional details

August 20, 2023
October 23, 2023