Synopsis of Emission Factors and Plume Evolution from Wildfires and Aged Regionally Distributed Smoke Sampled during BBOP

 

Authors

Larry Kleinman — Brookhaven National Laboratory
Arthur J Sedlacek — Brookhaven National Laboratory
Ernie R. Lewis — Brookhaven National Laboratory
Stephen R. Springston — Brookhaven National Laboratory
Jian Wang — Washington University in St. Louis
Duli Chand — Pacific Northwest National Laboratory
John E Shilling — Pacific Northwest National Laboratory
William Patrick Arnott — University of Nevada Reno
Ed Fortner — Aerodyne Research, Inc.
Andrew Freedman — Aerodyne Research, Inc.
Timothy B Onasch — Aerodyne Research, Inc.
Qi Zhang — University of California, Davis
Robert James Yokelson — University of Montana
Kouji Adachi — Meteorological Research Institute
Peter R. Buseck — Arizona State University

Category

Absorbing aerosol

Description

During the first phase of the BBOP field campaign, conducted in the Pacific Northwest, the DOE G-1 aircraft was used to follow the time evolution of smoke from wildland fires from near the point of emission until the plumes had aged for several hours. Older plumes were also sampled, in particular, in conjunction with surface observations at Mount Bachelor Observatory. In eight wildfire plumes, flights included multiple transects at varying downwind distances that allow us to determine the chemical and physical time evolution of trace gases and aerosols in a pseudo-Lagrangian frame that encompasses the first hours of atmospheric processing. We use the eight plume flights and measurements in more aged smoke to identify common features. The single scatter albedo downwind of the observed fires, and often close to the fires, are of order 0.9 or greater, indicating that under most conditions the smoke will have a cooling direct radiative effect. Although aerosol composition may change with time, on average, there is little change in aerosol mass – normalized to CO. Particle growth accounts for up to a doubling in light scattering and mass scattering efficiency. Aerosol sulfate is mainly primary (emitted), whilst aerosol nitrate is mainly secondary (formed downwind). Ozone production efficiency (ozone produced per molecule of NOx consumed) is in the 2 – 5 range, similar to urban areas. High NOx concentrations near fires lead to rapid ozone production, rapid NOx loss, and ozone concentrations that can reach 200 ppb.