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| Titel |
An integrated model for Jupiter's dynamo action and mean jet dynamics |
| VerfasserIn |
Thomas Gastine, Johannes Wicht, Lúcia Duarte, Moritz Heimpel |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096431
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| Publikation (Nr.) |
 EGU/EGU2014-11938.pdf |
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| Zusammenfassung |
| Data from various space crafts revealed that Jupiter's large scale interior
magnetic field is very Earth-like. This is surprising since numerical
simulations have demonstrated that, for example, the radial dependence of
density, electrical conductivity and other physical properties, which is only
mild in the iron cores of terrestrial planets but very drastic in gas planets,
can significantly affect the interior dynamics. Jupiter's dynamo action is
thought to take place in the deeper envelope where hydrogen, the main
constituent of Jupiter's atmosphere, assumes metallic properties. The
potential interaction between the observed zonal jets and the deeper dynamo
region is an unresolved problem with important consequences for the magnetic
field generation. Here we present the first numerical simulation that is based
on recent interior models and covers 99% of the planetary radius (below the 1
bar level). A steep decease in the electrical conductivity over the outer 10%
in radius allowed us to model both the deeper metallic region and the outer
molecular layer in an integrated approach. The magnetic field very closely
reproduces Jupiter's known large scale field. A strong equatorial zonal jet
remains constrained to the molecular layer while higher latitude jets are
suppressed by Lorentz forces. This suggests that Jupiter's higher latitude jets
remain shallow and are driven by an additional effect not captured in our deep
convection model. The dynamo action of the equatorial jet produces a band of
magnetic field located around the equator. The unprecedented magnetic field
resolution expected from the Juno mission will allow to resolve this feature
allowing a direct detection of the equatorial jet dynamics at depth. Typical
secular variation times scales amount to around 750 yr for the dipole
contribution but decrease to about 5 yr at the expected Juno resolution
(spherical harmonic degree 20). At a nominal mission duration of one year Juno
should therefore be able to directly detect secular variation effects in the
higher field harmonics. |
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