MEANDERING SHALLOW ATMOSPHERIC JET AS A MODEL OF SATURN'S NORTH-POLAR HEXAGON
- Physics Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States)
- Atmospheric and Planetary Sciences Department, Hampton University, Hampton VA 23668 (United States)
- Solar System Exploration Division, NASA/GSFC, Greenbelt MD 20771 (United States)
The Voyager flybys of Saturn in 1980–1981 revealed a circumpolar Hexagon at ∼78° north planetographic latitude that has persisted for over 30 Earth years, more than one Saturn year, and has been observed by ground-based telescopes, Hubble Space Telescope and multiple instruments on board the Cassini orbiter. Its average phase speed is very slow with respect to the System III rotation rate, defined by the primary periodicity in the Saturn Kilometric Radiation during the Voyager era. Cloud tracking wind measurements reveal the presence of a prograde jet-stream whose path traces the Hexagon’s shape. Previous numerical models have produced large-amplitude, n = 6, wavy structures with westward intrinsic phase propagation (relative to the jet). However, the observed net phase speed has proven to be more difficult to achieve. Here we present numerical simulations showing that instabilities in shallow jets can equilibrate as meanders closely resembling the observed morphology and phase speed of Saturn’s northern Hexagon. We also find that the winds at the bottom of the model are as important as the winds at the cloud level in matching the observed Hexagon’s characteristics.
- OSTI ID:
- 22518958
- Journal Information:
- Astrophysical Journal Letters, Vol. 806, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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