Atmos. Chem. Phys. Discuss., 13, 26893-26931, 2013
© Author(s) 2013. 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.
Uncertainties in future climate predictions due to convection parameterisations
H. Rybka and H. Tost
Institute for Atmospheric Physics, University of Mainz, Mainz, Germany

Abstract. In the last decades several convection parameterisations have been developed to consider the impact of small-scale unresolved processes in Earth System Models associated with convective clouds. Global model simulations, which have been performed under current climate conditions with different convection schemes, significantly differ among each other in the simulated transport of trace gases and precipitation patterns due to the parameterisation assumptions and formulations, e.g. the simplified treatment of the cloud microphysics. Here we address sensitivity studies comparing four different convection schemes under alternative climate conditions (doubling of the CO2 concentrations) to identify uncertainties related to convective processes. The increase in surface temperature reveals regional differences up to 4 K dependent on the chosen convection parameterisation. The increase in upper tropospheric temperature affects the amount of water vapour transported to the lower stratosphere. Furthermore, the change in transporting short-lived pollutants within the atmosphere is highly ambiguous for the lower and upper troposphere. Finally, cloud radiative effects have been analysed uncovering a shift in different cloud types in the tropics.

Citation: Rybka, H. and Tost, H.: Uncertainties in future climate predictions due to convection parameterisations, Atmos. Chem. Phys. Discuss., 13, 26893-26931, doi:10.5194/acpd-13-26893-2013, 2013.
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