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

• 成果类型: Article
• 署名作者: Bloxham, Jeremy; Cao, Hao; Stevenson, David J.; Connerney, John E. P.; Bolton, Scott J.
• 署名单位: Harvard University; University of California System; University of California Los Angeles; California Institute of Technology; National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; Southwest Research Institute
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5283
• DOI: 10.1038/s41586-024-07046-3
• 发表日期: 2024-03-07
• 关键词: magnetic-field; convection; fluid; core; FLOW

摘要

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 revealed1-3 and been shown to arise, in part, from an axisymmetric, equatorial jet2. 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 flow4-9) 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 oscillation10 (a cylindrically symmetric oscillating flow about the rotation axis) or a localized Alfven 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. An axisymmetric, equatorial jet in Jupiter's interior has a wavelike fluctuation with a 4-year period, revealing hidden aspects of the magnetic field within the metallic hydrogen region and constraining the dynamo that generates the magnetic field.