New particle formation in Remote Northern American Forests under the Sulfur Plume Influence
Abstract
About 30% of the Earth’s land surface is covered by various types of forests. Forest emitted biogenic volatile organic compounds (BVOCs) affect atmospheric photochemistry, aerosol loading, and radiative forcing over forests. Many forests are experiencing rapid changes in environmental conditions as a result of forest succession due to climate change. This also affects local BVOC chemistry and aerosol formation and growth in near canopy environments, thereby altering the climatic effects of forests. We observed aerosol sizes and nucleation precursors during Community Atmosphere-Biosphere Interactions Experiments (CABINEX) collaborative research in the remote Michigan forests in the summer 2009, in order to understand the new particle formation processes in BVOC rich, remote northern American forests. Our observations show that occurrence of ultrafine particles in the remote Michigan forest site was rare, even in the presence of high concentrations of biogenically emitted isoprene and its oxidation products during the summer 2009. NPF was observed on two occasions during 4 weeks of measurements. Analysis based on both the ground- and satellite-based measurements of key trace gas species show that these two events were strongly influenced by anthropogenic SO2 plumes transported from regional power plants. Microphysical box modeling simulations, constrained by the measured SO2, OH, and H2SO4 and other key atmospheric parameters, show that ion nucleation involving high concentrations of SO2 and/or H2SO4 is a likely pathway to explain the observed ultrafine particles, while binary and ternary homogeneous nucleation processes failed to reproduce atmospheric observations. Our results indicate that despite stringent air quality regulations in North America, the threat to remote forests from air pollution still persist, contributing to formation of aerosol particles over forested areas and must be accounted for in models to accurately predict the impact of new particle formation on climate.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.A33F0241K
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0315 ATMOSPHERIC COMPOSITION AND STRUCTURE / Biosphere/atmosphere interactions