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[1] For this conceptual study we focus on the impact of interactive stratospheric ozone chemistry on the tropospheric circulation, using the atmosphere-ocean-sea ice general circulation model (AOGCM) ECHO-GiSP with simplified stratospheric chemistry. The model covers the troposphere and middle atmosphere up to 80 km height. Our results show a clear sensitivity of the tropospheric circulation dynamics to the stratospheric chemistry. With enabled interactive stratospheric chemistry the model tends to the negative phase of the Arctic Oscillation (AO) mode. This also includes an enhanced midlatitudinal planetary and synoptic scale wave activity. The strengthening of the synoptic scale waves leads to stronger stormtracks, while the planetary scale waves show larger changes outside this particular latitudes. Another tropospheric region, which is influenced by interactive stratospheric chemistry effects, is the tropical troposphere. Due to changes in lower stratospheric ozone concentrations a significant cooling appears in the positive AO-phase compared to the negative phase. Citation: Brand, S., K. Dethloff, and D. Handorf (2008), Tropospheric circulation sensitivity to an interactive stratospheric ozone, Geophys. Res. Lett., 35, L05809,

Effects of post-larval abalone (Haliotis rubra) grazing on the epiphytic diatom assemblage of coralline red algae

A new globally uniform Lagrangian transport scheme for large ensembles of passive tracer particles is presented and applied to wind data from a coupled atmosphere-ocean climate model that includes interactive dynamical feedback with stratospheric chemistry. This feedback from the chemistry is found to enhance large-scale meridional air mass exchange in the northern winter stratosphere as well as intrusion of stratospheric air into the troposphere, where both effects are due to a weakened polar vortex.

Based on 150-year equilibrium simulations using the atmosphere-ocean-sea ice general circulation model (AOGCM) ECHOGiSP, the southern hemisphere winter circulation is examined focusing on tropo-stratosphere coupling and wave dynamics. The model covers the troposphere and strato-mesosphere up to 80 km height and includes an interactive stratospheric chemistry. Compared to the reference simulation without interactive chemistry, the interactive simulation shows a weaker polar vortex in the middle atmosphere and is shifted towards the negative phase of the Antarctic Oscillation (AAO) in the troposphere. Differing from the northern hemisphere winter situation, the tropospheric planetary wave activity is weakened. A detailed analysis shows, that the modelled AAO zonal mean signal behaves antisymmetrically between troposphere and strato-mesosphere. This conclusion is supported by reanalysis data and a discussion of planetary wave dynamics in terms of Eliassen-Palm fluxes. Thereby, the tropospheric planetary wave activity appears to be controlled from the middle atmosphere.