Polar Vortices in Planetary Atmospheres

Summary A common feature of planetary atmospheres is the occurrence of polar vortices, which play an important role in atmospheric dynamics, chemistry, and microphysics. These vortices are observed on both terrestrial and giant planets, but there is a large diversity in their morphology and evolution. This diversity occurs within terrestrial or giant planets and can even occur for vortices on the same planet. It is possible to separate the vortices into either a planetary-scale structure with strongest circumpolar cyclonic flow in mid- to high latitudes or smaller, compact cyclones that are located within the polar region. Differences can still exist within a type, including whether there is one or multiple small vortices within the polar region. However, there are common aspects. On all terrestrial planets, there are planetary-scale vortices whose edge occurs at the descending edge of a meridional circulation (Hadley) cell, while the smaller vortices on Venus, Saturn, and Jupiter have features that resemble Earth’s tropical cyclones. More comparative studies are needed to better understand the processes controlling the vortices on different planets, and to characterize the polar vortices that may occur on exoplanets.