Events Calendar

Closing the Gap on Missing Sources of Organic Aerosol in the Atmosphere

Speaker: Christopher Hennigan, Carnegie Mellon University

Talk Title: Closing the Gap on Missing Sources of Organic Aerosol in the Atmosphere

Abstract: Aerosols, or particulate matter, are ubiquitous components of the atmosphere that exert important impacts on human health and global climate, though our understanding of these effects is far from clear. A better characterization of aerosol physical and chemical properties, including their sources and fate, is vital in obtaining a more accurate assessment of their contribution to climate change and in devising mitigation strategies with public health in mind. Extensive ambient measurements have demonstrated that organic compounds comprise a significant fraction of aerosol mass in many locations globally. Our knowledge of this organic aerosol (OA), however, is incomplete, as evidenced by the systematic underprediction of OA concentrations by state-of-the-art computer models. Recent research efforts have intensified to identify this “missing” source of OA, with many hypotheses emerging. Measurements conducted in Atlanta point to liquid water associated with aerosols as an important OA source that has not been considered previously. This mechanism involves the dissolution and subsequent reaction of soluble organic gases in the aerosol aqueous phase. It is likely different from processes occurring in cloud and fog water due to extreme concentration differences. Previous studies have ignored this possibility due to the relatively small amount of water associated with fine particles (aerosols with diameters smaller than 2.5 µm); however, our results provide strong evidence that this pathway contributes significantly to ambient OA concentrations. This mechanism is likely to be important in other locations, as well, and may represent the dominant source of OA missing from current models.

Host: Sonny Astani Dept. of Civil and Environmental Engineering

Location: Kaprielian Hall (KAP) - 209

Audiences: Everyone Is Invited

Contact: Erin Sigman