Black carbon from biomass burning

 
Poster PDF

Authors

Manvendra K. Dubey — Los Alamos National Laboratory
Allison C Aiken — Los Alamos National Laboratory
Kyle Gorkowski — Los Alamos National Laboratory
Claudio Mazzoleni — Michigan Technological University
Shang Liu — Los Alamos National Laboratory

Category

Aerosol Properties

Description

Approximately 50% of black carbon (BC) aerosols come from wildfires and are estimated to contribute up to ~0.6 W/m2 warming of the atmosphere globally. Organic carbon (OC) from fires condenses and/or mixes with BC resulting in an overall lower forcing of 0.03±0.12 Wm-2 from biomass burning. However, this reduction depends strongly on the composition of the carbonaceous aerosols and on the mixing state of OC and BC. Detailed model treatments and laboratory measurements indicate that a BC core coated with a non-absorbing OC layer enhances absorption with a positive climate forcing.

However, the real-time identification of the coating on this internally mixed BC in the field has only recently become detectable with the analysis of lag times between the scattering and incandescence signals in measurements from the single particle soot photometer (SP2). Direct online measurements of BC are made with the SP2, which measures the mass of the particles by incandescence on an individual particle basis, from nearby and aged wildfires in addition to those produced in the laboratory. We investigate BC in concentrated wildfire plumes from the two largest wildfires in New Mexico’s history with different ages and compare them to BC from indoor generation from single-source fuels (e.g., ponderosa pine) sampled during the Fire Lab At Missoula Experiments IV (FLAME-IV) at the US Forest Service Rocky Mountain Research Station’s Fire Science Laboratory in Missoula, Montana in November 2012. Plumes from the Las Conchas (LC) Fire, a wildfire that occurred in July–August of 2011 and burned ~157K acres, were sampled in the near-field after only a few hours of aging. Older plumes from the Whitewater Baldy (WB) Fire (May–June 2012) that burned ~300K acres were sampled from further afield with an aging period of 7–9 hours. FLAME-IV includes real-time sampling from direct emissions, well-mixed samples, and aging studies.