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

Creators: Bloxham, Jeremy; Cao, Hao; Stevenson, David J.¹; Connerney, John E. P.; Bolton, Scott J.

1. California Institute of Technology

Abstract

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^1,2,3 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 flow^4,5,6,7,8,9) 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 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.

Copyright and License

© The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Acknowledgement

We acknowledge support from the NASA Juno project.

Contributions

J.B. conceived the study, analysed the data and wrote the manuscript. H.C. contributed to the study through numerous discussions and suggestions. D.J.S. (chair of the Juno Interiors Working Group), J.P.E.C. (Juno mission deputy principal investigator and magnetometer lead scientist) and S.J.B. (Juno mission principal investigator) contributed to the writing and editing of the manuscript.

Data Availability

All data used in this study are available from the NASA Planetary Data System (https://pds.nasa.gov). The 42-orbit model can be downloaded from https://doi.org/10.7910/DVN/HFFI7A. Source data are provided with this paper.

Code Availability

Example code to read the 42-orbit model can be downloaded from https://doi.org/10.7910/DVN/HFFI7A.

Conflict of Interest

The authors declare no competing interests.

Files

Name	Size	Download all
s41586-024-07046-3.pdf md5:5c8c0bdc6913a78b9f6ca4925fedb968	1.9 MB	Preview Download
41586_2024_7046_MOESM1_ESM.xlsx md5:f5ff22a5db2dea66f526136cb8a42345	10.1 kB	Download

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes