Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1 H. Tost, P. Jöckel, A. Kerkweg, A. Pozzer, R. Sander, and J. Lelieveld Atmospheric Chemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, 55020 Mainz, Germany
Abstract. The representation of cloud and precipitation chemistry and subsequent
wet deposition of trace constituents in global atmospheric chemistry
models is associated with large uncertainties.
To improve the simulated trace gas distributions we apply the new
submodel SCAV, which includes detailed cloud and precipitation
chemistry and present results of the atmospheric chemistry general
circulation model ECHAM5/MESSy1.
A good agreement with observed wet deposition fluxes for species
causing acid rain is obtained.
The new scheme enables prognostic calculations of the pH of clouds and
precipitation, and these results are also in accordance with observations.
We address the influence of detailed cloud and precipitation chemistry
on trace constituents based on sensitivity simulations.
The results confirm previous results from regional scale and box models,
and we extend the analysis to the role of aqueous phase chemistry on the
Some species are directly affected through multiphase removal processes,
and many also indirectly through changes in oxidant concentrations,
which in turn have an impact on the species lifetime.
While the overall effect on tropospheric ozone is relatively small
(<10%), regional effects on O3 can reach ≈20%, and
several important compounds (e.g., H2O2, HCHO) are
substantially depleted by clouds and precipitation.
Citation: Tost, H., Jöckel, P., Kerkweg, A., Pozzer, A., Sander, R., and Lelieveld, J.: Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1, Atmos. Chem. Phys., 7, 2733-2757, doi:10.5194/acp-7-2733-2007, 2007.