Mountain-wave Induced Polar Stratospheric Clouds with ICON-ART: An Example at the Antarctic Peninsula
<p>Polar Stratospheric Clouds (PSCs) play a key role in explaining ozone depletion on large<br>scales as well as on regional scales. Mountain waves can be formed in the lee of a mountain<br>in a stably stratified atmosphere. They can propagate upwards into the stratosphere and<br>induce temperature changes in the order of 10 to 15 K. Thus, large PSCs localised around the<br>mountain ridge can be formed, leading to increased chlorine activation and subsequently to<br>a larger ozone depletion. It was estimated that 30 % of the southern hemispheric PSCs can<br>be explained by mountain waves. However, for the direct simulation of mountain-wave<br>induced PSCs, the mountains have to be represented adequately in global chemistry climate<br>models which was a challenge in the past due to too low horizontal resolution.</p><p><br>The ICOsahedral Nonhydrostatic (ICON) modelling framework with its extension for Aerosols<br>and Reactive Trace gases (ART) includes a PSC scheme coupled to the atmospheric chemistry<br>in the model. The PSC scheme calculates the formation of all three PSC types independently<br>resulting in the calculation of the heterogeneous reaction rates of chlorine and bromine<br>species on the surface of PSCs. ICON-ART provides the possibility of local grid refinement<br>with two-way interaction. With this, the grid around a mountain can be refined so that<br>mountain waves can be directly simulated in this region with a feedback to the coarser<br>global resolution.</p><p><br>In this study, we show the formation of mountain-wave induced PSCs with ICON-ART for the<br>example of a mountain wave event in July 2008 around the Antarctic Peninsula. It is<br>evaluated with satellite measurements of AIRS and CALIOP and its impact on chlorine and<br>bromine activation as well as on the ozone depletion in the southern hemisphere are<br>analysed. We demonstrate that the effect of mountain-wave induced PSCs can be<br>represented in the coarser global grid by using local grid refinement with two-way<br>interaction. Thus, this study bridges the gap between directly simulated mountain-wave<br>induced PSCs and their representation in a global simulation.</p>