Atmos. Chem. Phys. Discuss., 5, 7361-7386, 2005
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The impact of ice uptake of nitric acid on atmospheric chemistry
R. von Kuhlmann1,* and M. G. Lawrence1
1Max-Planck-Institute for Chemistry, Department of Airchemistry, Mainz, Germany
*now at: German Aerospace Center (DLR), Bonn, Germany

Abstract. The potential impact of the uptake of HNO3 on ice on the distribution of NOy species, ozone and OH has been assessed using the global scale chemistry-transport model MATCH-MPIC. Assuming equilibrium uptake according to dissociative Langmuir theory results in significant reductions of gas phase HNO3. Comparison to a large set of observations provides support that significant uptake of HNO3 on ice is occurring, but the degree of the uptake cannot be inferred from this comparison alone. Sensitivity simulations show that the uncertainties in the total amount of ice formation in the atmosphere and the actual expression of the settling velocity of ice particles only result in small changes in our results. The largest uncertainty is likely to be linked to the actual theory describing the uptake process. The inclusion of non-methane hydrocarbon chemistry buffers the overall effect of neglected uptake of HNO3 on ice. The calculated overall effect on upper tropospheric ozone concentrations and the tropospheric methane lifetime are moderate to low. These results support a shift in the motivation for future experimental and theoretical studies of HNO3-ice interaction towards the role of HNO3 in hydrometeor surface physics.

Citation: von Kuhlmann, R. and Lawrence, M. G.: The impact of ice uptake of nitric acid on atmospheric chemistry, Atmos. Chem. Phys. Discuss., 5, 7361-7386, doi:10.5194/acpd-5-7361-2005, 2005.
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