Researchers report a plausible mechanism for the formation of Saturn's polar hexagon. A hexagon-shaped atmospheric flow pattern surrounding Saturn's north pole has been consistently observed over the past 40 years. Various models have reproduced this phenomenon using externally imposed constraints, but how such a stable pattern can spontaneously arise from atmospheric turbulence remains poorly understood. Rakesh Yadav and Jeremy Bloxham report the results of model simulations of deep turbulent compressible convection in the outer layers of Saturn's atmosphere. The simulations produced latitudinal flow jets of alternating direction, resembling those observed on Saturn. The simulations further resulted in a large cyclone centered on the north pole, surrounded by three anticyclonic vortices, several smaller cyclonic vortices, and a strong eastward jet at approximately 60 degrees north of the equator. This eastward jet formed a polygonal shape with nine edges as a result of being pinched by the surrounding vortices. These vortices are apparent deep beneath the surface of the simulation but become obscured by incoherent convection close to the surface as a result of weaker flow than the jets or the polar vortex. The results suggest a potential mechanism behind the polar hexagon on Saturn, according to the authors.
Article #20-00317: "Deep rotating convection generates the polar hexagon on Saturn," by Rakesh K. Yadav and Jeremy Bloxham.
MEDIA CONTACT: Rakesh K. Yadav, Harvard University, Cambridge, MA; tel: 850-225-9965; e-mail: rakesh_yadav@fas.harvard.edu
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Proceedings of the National Academy of Sciences