Science Update: Quantifying the role of orographic gravity waves on polar stratospheric cloud occurrence in the Antarctic and the Arctic

S. P. Alexander and co-authors quantify the proportion of polar stratospheric clouds (PSCs) due to orographic wave forcing in a recent JGR article. Looking at data from four winter seasons for both the Antarctic and Arctic they show that in the regions downstream of mountain ranges more than 75% of water ice PSCs and around 50% of a high number density liquid nitric acid trihydrate mixture class result from orographic wave activity. In the synoptically warmer Arctic 12% of all PSCs are attributed to orographic wave forcing, while for the Antarctic this proportion is much lower (5%). The full abstract can be found here.