Characterizations of Black Carbon Aerosols from Southeast U.S. Prescribed Fires and Western U.S. Wildfires

ANDREW METCALF, Dongli Wang, Clemson University

     Abstract Number: 791
     Working Group: Carbonaceous Aerosol

Abstract
Biomass burning from prescribed fires and wildfires are two important sources of carbonaceous aerosol in the atmosphere. Although the western U.S. receives noteworthy publicity for the wildfires which occur there almost every year, the southeastern U.S. actually has far more prescribed fires. Such fires have a significant impact on air quality and local visibility. However, field measurements of aerosol emissions from small, prescribed fires are relatively sparse. Black carbon (BC) is one of the important aerosol emissions from open biomass burning, affecting air quality and human health on regional scale. BC is also an efficient light-absorbing aerosol component and thus affects radiative transfer in the atmosphere. Optical properties are critical parameters determining the impacts of aerosol emissions on climate and are highly dependent on aerosol composition.

In this presentation, BC aerosol emissions from prescribed fires in the southeast U.S., from both historical and recent measurements, are compared to emissions from wildfires which predominantly occur in the western U.S. A scanning electrical mobility spectrometer (SEMS) is used to measure the total submicron aerosol size distributions, and a Single Particle Soot Photometer (SP2) is employed as the primary measurement of BC aerosol number and mass mixing ratios, mass and size distributions, and number fractions of coated and uncoated BC-containing aerosol particles. Measurements of western wildfires were conducted on an aircraft campaign, while measurements of southeastern prescribed fires were ground-based. Studying the difference in these two emission sources will provide information for emission inventories to better predict the impact on air quality and the climate system from BC aerosol.