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Zonal Flow Magnetic Field Interaction in the Semi-Conducting Region of Giant Planets

Cao, Hao and Stevenson, David J. (2017) Zonal Flow Magnetic Field Interaction in the Semi-Conducting Region of Giant Planets. Icarus, 296 . pp. 59-72. ISSN 0019-1035. http://resolver.caltech.edu/CaltechAUTHORS:20170525-112023100

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Abstract

All four giant planets in the Solar System feature zonal flows on the order of 100 m/s in the cloud deck, and large-scale intrinsic magnetic fields on the order of 1 Gauss near the surface. The vertical structure of the zonal flows remains obscure. The end-member scenarios are shallow flows confined in the radiative atmosphere and deep flows throughout the entire planet. The electrical conductivity increases rapidly yet smoothly as a function of depth inside Jupiter and Saturn. Deep zonal flows will inevitably interact with the magnetic field, at depth with even modest electrical conductivity. Here we investigate the interaction between zonal flows and magnetic fields in the semi-conducting region of giant planets. Employing mean-field electrodynamics, we show that the interaction will generate detectable poloidal magnetic field perturbations spatially correlated with the deep zonal flows. Assuming the peak amplitude of the dynamo α-effect to be 0.1 mm/s, deep zonal flows on the order of 0.1 – 1 m/s in the semi-conducting region of Jupiter and Saturn would generate poloidal magnetic perturbations on the order of 0.01 % – 1 % of the background dipole field. These poloidal perturbations should be detectable with the in-situ magnetic field measurements from the Juno mission and the Cassini Grand Finale. This implies that magnetic field measurements can be employed to constrain the properties of deep zonal flows in the semi-conducting region of giant planets.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.icarus.2017.05.015DOIArticle
http://www.sciencedirect.com/science/article/pii/S001910351630272XPublisherArticle
ORCID:
AuthorORCID
Cao, Hao0000-0002-6917-8363
Stevenson, David J.0000-0001-9432-7159
Additional Information:© 2017 Elsevier Inc. Received 9 June 2016, Revised 9 May 2017, Accepted 24 May 2017, Available online 25 May 2017. This work has been supported by NASA’s Juno mission and NASA’s Cassini Data Analysis and Participating Scientists (CDAPS) Program under grant number NNX15AL11G. We thank Chris Jones and an anonymous reviewer for their constructive comments.
Funders:
Funding AgencyGrant Number
NASANNX15AL11G
Subject Keywords:Jupiter; Saturn; Interiors; Magnetic Fields
Record Number:CaltechAUTHORS:20170525-112023100
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170525-112023100
Official Citation:Hao Cao, David J. Stevenson, Zonal flow magnetic field interaction in the semi-conducting region of giant planets, Icarus, Volume 296, 1 November 2017, Pages 59-72, ISSN 0019-1035, https://doi.org/10.1016/j.icarus.2017.05.015. (http://www.sciencedirect.com/science/article/pii/S001910351630272X)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77757
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:25 May 2017 18:29
Last Modified:05 Oct 2017 22:26

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