1British Antarctic Survey, NERC, Cambridge, UK
2Jülich Supercomputing Centre, Forschungszentrum Jülich, Jülich, Germany
3Department of Chemistry, University of Cambridge, Cambridge, UK
4National Institute of Water and Atmospheric Research, Auckland, New Zealand
5National Centre for Atmospheric Science, University of Cambridge, Cambridge, UK
6Met Office, Exeter, UK
7Karlsruhe Institute of Technology, Karlsruhe, Germany
Received: 31 May 2014 – Discussion started: 10 Jul 2014
Abstract. An important source of polar stratospheric clouds (PSCs), which play a crucial role in controlling polar stratospheric ozone depletion, is from the temperature fluctuations induced by mountain waves. However, this formation mechanism is usually missing in chemistry–climate models because these temperature fluctuations are neither resolved nor parameterised. Here, we investigate the representation of stratospheric mountain-wave-induced temperature fluctuations by the UK Met Office Unified Model (UM) at climate scale and mesoscale against Atmospheric Infrared Sounder satellite observations for three case studies over the Antarctic Peninsula. At a high horizontal resolution (4 km) the regional mesoscale configuration of the UM correctly simulates the magnitude, timing, and location of the measured temperature fluctuations. By comparison, at a low horizontal resolution (2.5° × 3.75°) the global climate configuration fails to resolve such disturbances. However, it is demonstrated that the temperature fluctuations computed by a mountain wave parameterisation scheme inserted into the climate configuration (which computes the temperature fluctuations due to unresolved mountain waves) are in relatively good agreement with the mesoscale configuration responses for two of the three case studies. The parameterisation was used to include the simulation of mountain-wave-induced PSCs in the global chemistry–climate configuration of the UM. A subsequent sensitivity study demonstrated that regional PSCs increased by up to 50% during July over the Antarctic Peninsula following the inclusion of the local mountain-wave-induced cooling phase.
Revised: 24 Nov 2014 – Accepted: 15 Dec 2014 – Published: 30 Jan 2015
Orr, A., Hosking, J. S., Hoffmann, L., Keeble, J., Dean, S. M., Roscoe, H. K., Abraham, N. L., Vosper, S., and Braesicke, P.: Inclusion of mountain-wave-induced cooling for the formation of PSCs over the Antarctic Peninsula in a chemistry–climate model, Atmos. Chem. Phys., 15, 1071-1086, doi:10.5194/acp-15-1071-2015, 2015.