1Carnegie Mellon University Center for Atmospheric Particle Studies, Pittsburgh, USA
2MIT Departments of Civil and Environmental Engineering and Chemical Engineering, Cambridge, USA
3Institute of Chemical Engineering and High Temperature Processes, FORTH, Patras, Greece
Received: 09 Aug 2011 – Discussion started: 05 Sep 2011
Abstract. We discuss the use of a two-dimensional volatility-oxidation space (2-D-VBS) to describe organic-aerosol chemical evolution. The space is built around two coordinates, volatility and the degree of oxidation, both of which can be constrained observationally or specified for known molecules. Earlier work presented the thermodynamics of organics forming the foundation of this 2-D-VBS, allowing us to define the average composition (C, H, and O) of organics, including organic aerosol (OA) based on volatility and oxidation state. Here we discuss how we can analyze experimental data, using the 2-D-VBS to gain fundamental insight into organic-aerosol chemistry. We first present a well-understood "traditional" secondary organic aerosol (SOA) system – SOA from α-pinene + ozone, and then turn to two examples of "non-traditional" SOA formation – SOA from wood smoke and dilute diesel-engine emissions. Finally, we discuss the broader implications of this analysis.
Revised: 20 Dec 2011 – Accepted: 22 Dec 2011 – Published: 16 Jan 2012
Donahue, N. M., Kroll, J. H., Pandis, S. N., and Robinson, A. L.: A two-dimensional volatility basis set – Part 2: Diagnostics of organic-aerosol evolution, Atmos. Chem. Phys., 12, 615-634, doi:10.5194/acp-12-615-2012, 2012.