Biomass-burning particle measurements: Characteristic composition and chemical processing : Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) and Pacific Exploration of Asian Continental Emissions (PEACE) experiments

The NOAA Lockheed Orion WP-3D aircraft intercepted a forest fire plume over Utah on 19 May 2002 during the Intercontinental Transport and Chemical Transformation (ITCT) mission. Large enhancements in acetonitrile (CH 3 CN), carbon monoxide (CO) and particle number were measured during the fire plume interception. In the 100 s plume crossing, the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument acquired 202 positive mass spectra from ionizing single particles in the 0.2-5 μm size range. These particles contained carbon, potassium, organics, and ammonium ions. No pure soot particles were sampled directly from the plume. By characterizing these particle mass spectra, a qualitative biomass-burning particle signature was developed that was then used to identify biomass-burning particles throughout ITCT. The analysis was extended to identify biomass-burning particles in four other missions, without the benefit of gas-phase biomass-burning tracers. During ITCT, approximately 33% of the particles sampled in the North American troposphere and 37% of the particles transported from Asia, not influenced by North American sources, were identified as biomass-burning particles. During the WB-57 Aerosol Mission (WAM), Atmospheric Chemistry of Combustion Emissions near the Tropopause (ACCENT) and ACCENT 2000 missions, 7% of stratospheric particles were identified as biomass-burning particles. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) this percentage increased to 52% because the regional stratosphere was strongly affected by an active fire season.