Thursday 07 Feb 2019Mars' annular polar vortices: Cause and stability

Dr William Seviour - University of Bristol

Harrison 103 14:30-16:30

In common with several other planetary bodies, Mars’ atmosphere has strong circumpolar zonal winds during winter, known as polar vortices. A distinctive feature of the Martian polar vortices is that they consist of an annulus of high potential vorticity (PV) with opposing meridional gradients on the equatorward and poleward sides, and a local minimum at the geographic pole. This finding is surprising given that a strip of uniform vorticity is barotropically unstable, a result going back to Rayleigh.

In this talk I will discuss recent and ongoing work aiming to understand the creation, maintenance, and stability of Mars’ annular polar vortices, as well as their impact on transport and mixing between high and low latitudes. This work makes use of observational reanalyses, a comprehensive general circulation model, and an idealized shallow water model. I will also discuss the potential for annular vortex dynamics to help explain the striking polygonal vortex clusters at Jupiter’s poles, as recently observed by the Juno mission.

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