Dynamo Action in the Steeply Decaying Conductivity Region of Jupiter-like Dynamo Models (1808.05356v1)

Abstract: The Juno mission is delivering spectacular data of Jupiter's magnetic field, while the gravity measurements finally allow constraining the depth of the winds observed at cloud level. However, to which degree the zonal winds contribute to the planet's dynamo action remains an open question. Here we explore numerical dynamo simulations that include an Jupiter-like electrical conductivity profile and successfully model the planet's large scale field. We concentrate on analyzing the dynamo action in the Steeply Decaying Conductivity Region (SDCR) where the high conductivity in the metallic Hydrogen region drops to the much lower values caused by ionization effects in the very outer envelope of the planet. Our simulations show that the dynamo action in the SDCR is strongly ruled by diffusive effects and therefore quasi stationary. The locally induced magnetic field is dominated by the horizontal toroidal field, while the locally induced currents flow mainly in the latitudinal direction. The simple dynamics can be exploited to yield estimates of surprisingly high quality for both the induced field and the electric currents in the SDCR. These could be potentially be exploited to predict the dynamo action of the zonal winds in Jupiter's SDCR but also in other planets.