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Published October 27, 2014 | Published
Journal Article Open

Aerosol emissions from prescribed fires in the United States: A synthesis of laboratory and aircraft measurements

Abstract

Aerosol emissions from prescribed fires can affect air quality on regional scales. Accurate representation of these emissions in models requires information regarding the amount and composition of the emitted species. We measured a suite of submicron particulate matter species in young plumes emitted from prescribed fires (chaparral and montane ecosystems in California; coastal plain ecosystem in South Carolina) and from open burning of over 15 individual plant species in the laboratory. We report emission ratios and emission factors for refractory black carbon (rBC) and submicron nonrefractory aerosol and compare field and laboratory measurements to assess the representativeness of our laboratory-measured emissions. Laboratory measurements of organic aerosol (OA) emission factors for some fires were an order of magnitude higher than those derived from any of our aircraft observations; these are likely due to higher-fuel moisture contents, lower modified combustion efficiencies, and less dilution compared to field studies. Nonrefractory inorganic aerosol emissions depended more strongly on fuel type and fuel composition than on combustion conditions. Laboratory and field measurements for rBC were in good agreement when differences in modified combustion efficiency were considered; however, rBC emission factors measured both from aircraft and in the laboratory during the present study using the Single Particle Soot Photometer were generally higher than values previously reported in the literature, which have been based largely on filter measurements. Although natural variability may account for some of these differences, an increase in the BC emission factors incorporated within emission inventories may be required, pending additional field measurements for a wider variety of fires.

Additional Information

© 2014 American Geophysical Union. Received 31 MAR 2014; Accepted 18 SEP 2014; Accepted article online 22 SEP 2014; Published online 16 OCT 2014. We thank the USFS Twin Otter pilots Bill Mank and Scott Miller and mechanic Steve Woods for their contribution to the SLOBB and SCREAM campaigns and the USFS JeffCo aircraft base, San Luis Aviation, Eagle Aviation, the NSF/NCAR Research Aviation Facility, and Ezra Levin for their contributions to the installation of instruments on the Twin Otter and its deployment to the field. Adaptation of the Twin Otter for atmospheric measurements and other support was provided by NSF grants ATM-0531055 and ATM-0936321 to R.Y. Prescribed fires were organized and carried out by John Maitland and forestry staff at Fort Jackson and Dan Ardoin at Vandenberg AFB. We also thank Jason McCarty of the Santa Barbara County Fire Department for conducting burns and providing fuels and weather information during SLOBB. Fuel inventories and other ground-based information were provided by Jim Reardon, Aaron Sparks, and Signe Leirfallom. We thank the USFS Fire Science Laboratory staff and the FLAMEIII participants for their contributions to the laboratory measurements. We also thank Shane Murphy, Roya Bahreini, and Ann Middlebrook for their suggestions and assistance inmodifying the Colorado State University AMS for aircraft operation during SCREAM; furthermore, Tim Onasch, Jose Jimenez, and Misha Schurman all contributed to discussions regarding AMS analysis of the SCREAM data. G.R. McMeeking's participation in FLAME-III was supported by the UK Royal Society. The California aircraft measurements were supported by the Strategic Environmental Research and Development Program (SERDP) projects SI-1648 and SI-1649 and the SP2 was supported by the UK Natural Environment Research Council (NERC). We acknowledge funding from the Joint Fire Science Program under project JFSP 11-1-5-12 for the South Carolina aircraft measurements and related AMS data analysis. The Fort Jackson study was supported by SERDP project RC-1649 administered partly through the Forest Service Research Joint Venture Agreement 08JV11272166039. Additional flight hours and SCREAM CRDS data were provided by Joint Fire Science Program project 08-1-6-09. To request copies of the data used in this paper, please contact the corresponding author. Finally, we would like to thank our editor, Lynn Russell, and the anonymous reviewers for their useful comments.

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Created:
August 22, 2023
Modified:
October 18, 2023