Title: Importing O3 precursors and aerosols to the North American free troposphere: An analysis of peroxyacetyl nitrate (PAN) and aerosol observations from Mount Bachelor


Abstract: This talk will have two parts, and there is something for everyone. We will begin with an analysis of the first consistent multi-year springtime measurements of peroxyacetyl nitrate (PAN) over the U.S. Pacific Northwest. PAN is an important constituent in the global atmosphere, responsible for redistributing reactive nitrogen. A limited number of case studies indicate that the NOx released from the thermal decomposition of imported PAN may represent a significant source of O3 to the eastern Pacific free troposphere. If changes in Asian NOx emissions are impacting O3 over North America, we expect a relatively larger parallel increase in PAN over the eastern Pacific. We will discuss factors driving the observed interannual variability in PAN at Mount Bachelor, including temperature and biomass burning. We will also explore whether consistent free tropospheric PAN observations could be the keystone to understanding increasing springtime O3 mixing ratios over western North America.
The latter portion of this talk will present measurements of aerosol optical properties and chemical composition made at Mount Bachelor. The overarching goal of this second project is to increase our understanding of how aging impacts the optical properties of Asian aerosols, particularly biomass burning smoke, industrial pollution and dust. We will explore two questions by examining 7 aerosol plumes of Asian origin observed at Mount Bachelor. 1) Are differences in the intensive optical properties of Asian aerosols observed over the western U.S. linked to variations in composition? 2) How do the aerosol optical properties observed in plumes of Asian origin over the western U.S. differ from those observed closer to the Asian source region? Finally, we investigate how the natural and anthropogenic aerosol components, such as mineral dust and secondary sulfate, contribute to the overall optical properties.




http://www.atmos.washington.edu/~efischer/