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Atmos. Chem. Phys., 11, 3303-3318, 2011
www.atmos-chem-phys.net/11/3303/2011/ doi:10.5194/acp-11-3303-2011 © Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License. |
A two-dimensional volatility basis set: 1. organic-aerosol mixing thermodynamics
Carnegie Mellon University Center for Atmospheric Particle Studies, Pittsburgh, USA
Abstract. We develop the thermodynamic underpinnings of a two-dimensional volatility basis set (2D-VBS) employing saturation mass concentration (Co) and the oxygen content (O:C) to describe volatility, mixing thermodynamics, and chemical evolution of organic aerosol. The work addresses a simple question: "Can we reasonably constrain organic-aerosol composition in the atmosphere based on only two measurable organic properties, volatility and the extent of oxygenation?" This is an extension of our earlier one-dimensional approach employing volatility only (C* = γ Co, where γ is an activity coefficient). Using available constraints on bulk organic-aerosol composition, we argue that one can reasonably predict the composition of organics (carbon, oxygen and hydrogen numbers) given a location in the Co – O:C space. Further, we argue that we can constrain the activity coefficients at various locations in this space based on the O:C of the organic aerosol.
Citation: Donahue, N. M., Epstein, S. A., Pandis, S. N., and Robinson, A. L.: A two-dimensional volatility basis set: 1. organic-aerosol mixing thermodynamics, Atmos. Chem. Phys., 11, 3303-3318, doi:10.5194/acp-11-3303-2011, 2011.