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Published April 2006 | Published
Journal Article Open

A new inorganic atmospheric aerosol phase equilibrium model (UHAERO)


A variety of thermodynamic models have been developed to predict inorganic gas-aerosol equilibrium. To achieve computational efficiency a number of the models rely on a priori specification of the phases present in certain relative humidity regimes. Presented here is a new computational model, named UHAERO, that is both efficient and rigorously computes phase behavior without any a priori specification. The computational implementation is based on minimization of the Gibbs free energy using a primal-dual method, coupled to a Newton iteration. The mathematical details of the solution are given elsewhere. The model computes deliquescence behavior without any a priori specification of the relative humidities of deliquescence. Also included in the model is a formulation based on classical theory of nucleation kinetics that predicts crystallization behavior. Detailed phase diagrams of the sulfate/nitrate/ammonium/water system are presented as a function of relative humidity at 298.15 K over the complete space of composition.

Additional Information

© Author(s) 2006. This work is licensed under a Creative Commons License. Received: 17 August 2005 – Published in Atmos. Chem. Phys. Discuss.: 28 September 2005 Revised: 23 December 2005 – Accepted: 7 February 2006 – Published: 28 March 2006 Published by Copernicus GmbH on behalf of the European Geosciences Union. This work was supported by US Environmental Protection Agency grant X-83234201. The authors thank S. L. Clegg for providing the code for the PSC model based activity coefficient calculation. Edited by: F. J. Dentener

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