On the dynamical nature of Saturn’s North Polar hexagon
| Autor: | LMD |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Glaciology
Stratigraphy Institutional and Historical Statistical Nonlinear and Soft Matter Physics External Galaxies Physical Sciences and Mathematics Cosmology Relativity and Gravity Instrumentation Physics::Atmospheric and Oceanic Physics Non-linear Dynamics Computer Sciences Applied Mathematics Information Security Physics Ordinary Differential Equations and Applied Dynamics Partial Differential Equations Numerical Analysis and Computation Geology Other Earth Sciences Cosmochemistry Dynamic Systems Graphics and Human Computer Interfaces Physical Processes Other Physics Geophysics and Seismology Other Computer Sciences Statistics and Probability Astrophysics and Astronomy Artificial Intelligence and Robotics Databases and Information Systems The Sun and the Solar System OS and Networks Other Astrophysics and Astronomy Plasma and Beam Physics FOS: Mathematics Categorical Data Analysis Probability Statistical Theory Applied Statistics Design of Experiments and Sample Surveys Stars Interstellar Medium and the Galaxy Geomorphology Fluid Dynamics FOS: Earth and related environmental sciences Statistical Methodology Other Applied Mathematics Earth Sciences Special Functions Paleobiology Numerical Analysis and Scientific Computing Environmental Sciences Mathematics Tectonics and Structure |
| DOI: | 10.17605/osf.io/rvdmx |
| Popis: | An explanation of long-lived Saturn’s North Polar hexagonal circumpolar jetin terms of instability of the coupled system polar vortex - circumpolar jet isproposed in the framework of the rotating shallow water model, wherescarcely known vertical structure of the Saturn’s atmosphere is averaged out.The absence of a hexagonal structure at Saturn’s South Pole is explainedsimilarly. By using the latest state-of-the-art observed winds in Saturn’spolar regions a detailed linear stability analysis of the circumpolar jet isperformed (i) excluding (“jet-only” configuration), and (2) including(“jet+vortex” configuration) the north polar vortex in the system. A domainof parameters: latitude of the circumpolar jet and curvature of its azimuthalvelocity profile, where the most unstable mode of the system has azimuthalwavenumber 6, is identified. Fully nonlinear simulations are then performed,initialized either with the most unstable mode of small amplitude, or withthe random combination of unstable modes. It is shown that developingbarotropic instability of the “jet+vortex” system produces a long-livingstructure akin to the observed hexagon, which is not the case of the“jet-only” system, which was studied in this context in a number of papersin literature. The north polar vortex, thus, plays a decisive dynamical role.The influence of moist convection, which was recently suggested to be at theorigin of Saturn’s north polar vortex system in the literature, is investigatedin the framework of the model and does not alter the conclusions. |
| Databáze: | OpenAIRE |
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