Volume 629, September 2019
|Number of page(s)||11|
|Section||Planets and planetary systems|
|Published online||17 September 2019|
Dynamo action of the zonal winds in Jupiter
Max Planck Institute for Solar System Research,
2 IPGP, Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris-Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75005 Paris, France
3 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Physics building, Stocker Road, Exeter, EX4 4QL, UK
Accepted: 5 July 2019
The new data delivered by NASA’s Juno spacecraft significantly increase our understanding of the internal dynamics of Jupiter. The gravity data constrain the depth of the zonal flows observed at cloud level and suggest that they slow down considerably at a depth of about 0.96 rJ, where rJ is the mean radius at the one bar level. The magnetometer onboard Juno reveals the internal magnetic field of the planet. We combine the new zonal flow and magnetic field models with an updated electrical conductivity profile to assess the zonal-wind-induced dynamo action, concentrating on the outer part of the molecular hydrogen region of Jupiter where the conductivity increases very rapidly with depth. Dynamo action remains quasi-stationary and can therefore reasonably be estimated where the magnetic Reynolds number remains smaller than one, which is roughly the region above 0.96 rJ. We calculate that the locally induced radial magnetic field reaches rms values of about 10−6 T in this region and may just be detectable by the Juno mission. Very localized dynamo action and a distinct pattern that reflects the zonal wind system increases the chance to disentangle this locally induced field from the background field. The estimates of the locally induced currents also allow calculation of the zonal-flow-related Ohmic heating and associated entropy production. The respective quantities remain below new revised predictions for the total dissipative heating and total entropy production in Jupiter for any of the explored model combinations. Thus, neither Ohmic heating nor entropy production offer additional constraints on the depth of the zonal winds.
Key words: planets and satellites: magnetic fields / planets and satellites: gaseous planets / magnetohydrodynamics (MHD) / dynamo
© J. Wicht et al. 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.