AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Observations of Wildfire Smoke and Ozone at the Mt. Bachelor Observatory in Central Oregon
DAN JAFFE, Nicole Wigder, Pao Baylon, Jon Hee, Qi Zhang, Shan Zhou, Sonya Collier, Lawrence Kleinman, Arthur J. Sedlacek, University of Washington, Bothell, WA, USA
Abstract Number: 447 Working Group: Biomass Burning Aerosol: From Emissions to Impacts
Abstract Wildfires affect PM and O3 (ozone) across large areas of the Western US every summer. Over the past decade we have studied wildfire smoke using a variety of gas and aerosol observations at the Mt. Bachelor Observatory (MBO) in central Oregon, and combined these with satellite and aircraft data and models. In 2013, our usual observations were enhanced with Aerosol Mass Spectrometry and aircraft observations as part of the US Department of Energy (DOE) sponsored Biomass Burning Observation Project (BBOP). The overall pattern shows large fire-to-fire variability, which we are working to understand. From observations 12-48 hours downwind of wildfires at MBO, we find PM1 enhancement ratios of 0.06-0.42 micro-gram per cubic meter per ppbv of CO or 16-52 micro-grams per cubic meter per ppmv of CO2. The PM enhancement is strongly dependent on the modified combustion efficiency (MCE), with higher PM per unit of CO2 for more smoldering combustion. Comparing the single scattering albedo (SSA) measured at MBO vs. MCE to laboratory and near field fire emissions, we find that the single scattering is significantly higher 1-2 days downwind compared to recent emissions. This indicates important changes in the aerosol due to aging during transport. For the CO/O3 enhancement ratios we find values that can be negative up to a value of +0.51 ppbv per ppbv. In general we find that the CO/O3 enhancement ratio is higher at greater distances from the fire. NOx is an important factor in O3 production. The NOx/NOy ratio is a good indicator of positive O3 production. We also find that for many fires, NOx is rapidly sequestered in the form of PAN. This limits the near-field O3 production but likely increases it downwind.