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
N. M. Donahue, S. A. Epstein, S. N. Pandis, and A. L. Robinson
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.
 
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