Abstract View
Evolution of Black Carbon Coatings in Biomass Burning Plumes during FIREX-AQ
BRADEN MEDIAVILLA, Joseph Katich, Joshua P. Schwarz, Glenn Diskin, Richard Moore, Elizabeth Wiggins, Donald Blake, Barbara Barletta, Nicola Blake, Simone Meinardi, Anne Perring, Colgate University
Abstract Number: 571
Working Group: Carbonaceous Aerosol
Abstract
Uncertainties regarding the physical and optical properties of black carbon (BC) emissions, and their evolution in time, influence our ability to appropriately predict BC’s atmospheric lifetime and its radiative effect. Here we present the variability and evolution of BC-core mass median diameter and average coating thickness with fuel type and burn conditions for fires sampled during the Boise phase of FIREX-AQ. In nearly all cases, substantial growth is observed in coating thickness over time while the BC-core mass median diameter shows no clear trend. Coagulation rates, calculated based on bulk aerosol number concentrations and size distributions, are too small to explain these observations. When considering condensational growth, two regimes emerge: denser plumes show significant and rapid coating thickness growth in the absence of photochemistry while more dilute plumes show moderate, yet still notable, growth with increasing photochemical age. These two regimes are readily differentiated by examination of CO2 integrated over plume transects. The observed trends can be used to parameterize BC emissions from biomass burning sources for improved BC mixing state predictions.