Atmos. Chem. Phys. Discuss., 9, 16051-16083, 2009
© Author(s) 2009. This work is distributed
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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 influence of the vertical distribution of emissions on tropospheric chemistry
A. Pozzer1,2, P. Jöckel2, and J. Van Aardenne3
1The Cyprus Institute, Energy, Environment and Water Research Centre, Nicosia, Cyprus
2Max-Planck Institute of Chemistry, Air Chemistry Department, Mainz, Germany
3European Commission, DG Joint Research Centre, Ispra, Italy

Abstract. The atmospheric chemistry general circulation model EMAC (ECHAM5/MESSy atmospheric chemistry) is used to investigate the effect of height dependent emissions on tropospheric chemistry. In a sensitivity simulation, anthropogenic and biomass burning emissions are released in the lowest model layer. The resulting tracer distributions are compared to those of a former simulation applying height dependent emissions. Although the differences between the two simulations in the free troposphere are small (less than 5%), large differences are present in polluted regions at the surface, in particular for NOx (more than 100%) and non-methane hydrocarbons (up to 30%), whereas for OH the differences at the same locations are somewhat lower (15%). Global ozone formation is virtually unaffected by the choice of the vertical distribution of emissions. Nevertheless, local ozone changes can be up to 30%. Model results of both simulations are further compared to observations from field campaigns and to data from measurement stations. The two simulations show no significant differences when compared to aircraft observations. In contrast, for measurements from surface stations, the simulation with emissions in the lowest model layer gives a 20% lower correlation to the observations compared to the simulation with height dependent emissions.

Citation: Pozzer, A., Jöckel, P., and Van Aardenne, J.: The influence of the vertical distribution of emissions on tropospheric chemistry, Atmos. Chem. Phys. Discuss., 9, 16051-16083, doi:10.5194/acpd-9-16051-2009, 2009.
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