Parameterization of N₂O₅ reaction probabilities on the surface of particles containing ammonium, sulfate, and nitrate

J. M. Davis (1) , P. V. Bhave (2) , K. M. Foley (2)

1 Atmospheric and Environmental Systems Modeling Division
2 ARL - NOAA Air Resources Laboratory

A comprehensive parameterization was developed for the heterogeneous reaction probability (?) of N₂O₅ as a function of temperature, relative humidity, particle composition, and phase state, for use in advanced air quality models. The reaction probabilities on aqueous NH₄HSO₄, (NH₄)₂SO₄, and NH₄NO₃ were modeled statistically using data and uncertainty values compiled from seven different laboratory studies. A separate regression model was fit to laboratory data for dry NH₄HSO₄ and (NH₄)₂SO₄ particles, yielding lower ? values than the corresponding aqueous parameterizations. The regression equations reproduced 79% of the laboratory data within a factor of two and 53% within a factor of 1.25. A fixed value was selected for ? on ice-containing particles based on a review of the literature. The combined parameterization was applied under atmospheric conditions representative of the eastern United States using 3-dimensional fields of temperature, relative humidity, sulfate, nitrate, and ammonium, obtained from a recent Community Multiscale Air Quality model simulation. The resulting spatial distributions of ? were contrasted with three other parameterizations that have been applied in air quality models in the past and with atmospheric observational determinations of ?. Our results highlight a critical need for more laboratory measurements of ? at low temperature and high relative humidity to improve model simulations of N₂O₅ hydrolysis during wintertime conditions.

Domaines: Océan, Atmosphère

J. M. Davis, P. V. Bhave, K. M. Foley. Parameterization of N₂O₅ reaction probabilities on the surface of particles containing ammonium, sulfate, and nitrate. Atmospheric Chemistry and Physics Discussions, 2007, 7 (6), pp.16119-16153. ⟨hal-00303176⟩