A rapidly time-varying equatorial jet in Jupiter's deep interior

Planetary magnetic fields provide a window into the otherwise largely inaccessible dynamics of a planet's deep interior. In particular, interaction between fluid flow in electrically conducting interior regions and the magnetic field there gives rise to observable secular variation (time depend...

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Bibliographic Details
Published in:Nature (London) 2024-03, Vol.627 (8002), p.64-66
Main Authors: Bloxham, Jeremy, Cao, Hao, Stevenson, David J, Connerney, John E P, Bolton, Scott J
Format: Article
Language:English
Subjects:
Alfven waves
Convective flow
Fluid flow
Hydrogen
Jupiter
Jupiter magnetic field
Magnetic fields
Magnetohydrodynamic waves
Metallic hydrogen
Orbits
Oscillating flow
Planetary interiors
Planetary magnetic fields
Secular variations
Time dependence
Velocity
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Summary:Planetary magnetic fields provide a window into the otherwise largely inaccessible dynamics of a planet's deep interior. In particular, interaction between fluid flow in electrically conducting interior regions and the magnetic field there gives rise to observable secular variation (time dependency) of the externally observed magnetic field. Secular variation of Jupiter's field has recently been revealed and been shown to arise, in part, from an axisymmetric, equatorial jet . Whether this jet is time dependent has not previously been addressed, yet it is of critical importance for understanding the dynamics of the planet's interior. If steady, it would probably be a manifestation of deep dynamo convective flow (and jets are anticipated as part of that flow ) but if time dependent on a timescale much shorter than the convective turnover timescale of several hundred years, it would probably have a different origin. Here we show that the jet has a wavelike fluctuation with a period of roughly 4 years, strongly suggestive of the presence of a torsional oscillation (a cylindrically symmetric oscillating flow about the rotation axis) or a localized Alfvén wave in Jupiter's metallic hydrogen interior. This opens a pathway towards revealing otherwise hidden aspects of the magnetic field within the metallic hydrogen region and hence constraining the dynamo that generates Jupiter's magnetic field.
ISSN:0028-0836
1476-4687
DOI:10.1038/s41586-024-07046-3