Polar vortices—regions of strong zonal winds encircling the winter pole—are near-ubiquitous features of planetary atmospheres. Acting to confine polar air, they enable unique dynamical and chemical processes to occur. On Earth, this includes influencing extreme weather events and the formation of the Antarctic ozone hole. Studying and comparing the polar vortices of different solar system atmospheres enables us to build a deeper understanding of their dynamics. Besides Earth, the two best-observed polar vortices of terrestrial planets are those of Mars and Titan.
In this talk I will give an overview of some recent work aiming to better understand the polar vortices of Mars and Titan using observational data and a hierarchy of numerical models. In contrast to Earth, both polar vortices have an annular potential vorticity structure, with a local minimum at the geographic pole. This result is surprising given that a strip of uniform vorticity is barotropically unstable (a result going back to Rayleigh), suggesting there must be some sustaining mechanism. I will discuss how these structures may be related to chemical processes in the atmospheres of both planetary bodies, and, in turn, how they may impact the transport and mixing of important trace species. Along the way I will draw parallels between our knowledge of planetary polar vortices today, and that of Earth’s polar vortices following the discovery of the ozone hole and the dawn of the satellite age.