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The formation of new aerosol from the gas phase is commonly represented in atmospheric modeling with parameterizations of the steady state nucleation rate. Present parameterizations are based on classical nucleation theory or on nucleation rates calculated with a numerical aerosol model. These parameterizations reproduce aerosol nucleation rates calculated with a numerical aerosol model only imprecisely. Additional errors can arise when the nucleation rate is used as a surrogate for the production rate of particles of a given size. We discuss these errors and present a method which allows a more precise calculation of steady state sulfate aerosol formation rates. The method is based on the semi-analytical solution of an aerosol system in steady state and on parameterized rate coefficients for H<sub>2</sub>SO<sub>4</sub> uptake and loss by sulfate aerosol particles, calculated from laboratory and theoretical thermodynamic data.

_{4})$_(x)$(HNO

_{3})$_(y)$, J. Phys. Chem. A, 105, 10 867–10 873, 2001. ]]>

_{2}SO

_{4}, and H

_{2}O cluster ions, Ph.D. thesis, Univ. of Colo., Boulder, 2002. ]]>

_{4}and H

_{2}O. 1. Positive Ions, J. Phys. Chem. A, 107, 9800–9811, 2003a. ]]>

_{4}and H

_{2}O. 2. Measurements and ab Initio Structures of Negative Ions, J. Phys. Chem. A, 107, 9812–9824, 2003b. ]]>

_{4}-NH

_{3}-H

_{2}O vapors, J. Geophys. Res., 107, 6–1, \doi10.1029/2002JD002132, 2002. ]]>