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 *now at: German Aerospace Center (DLR), Bonn
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 and the value
of the initial uptake coefficient.
The inclusion of non-methane hydrocarbon
chemistry partially compensates for the absence of HNO3 uptake on ice when this is neglected
in the model.
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
Citation: von Kuhlmann, R. and Lawrence, M. G.: The impact of ice uptake of nitric acid on atmospheric chemistry, Atmos. Chem. Phys., 6, 225-235, doi:10.5194/acp-6-225-2006, 2006.