The Internal Structure and Dynamics of Jupiter Unveiled by a High‐Resolution Magnetic Field and Secular Variation Model

Abstract

The interior of the giant planets of our Solar System can be described in simple terms as consisting of a core of unknown composition surrounded by fluid envelopes (Guillot, 2005). For Jupiter, the core could be small and dense, but also large and dilute (Wahl et al., 2017). The overlying envelopes consist of an inner layer of metallic hydrogen and an outer layer of molecular hydrogen. Recent experimental results describe a transition H-He demixing layer, suggesting Helium rain between depths 0.68 and 0.84 R J (Jupiter's equatorial radius, 1 R J = 71,492 km) (Brygoo et al., 2021). The high temperature and pressure inside the planet renders it electrically conducting. Convection in the electrically conductive metallic hydrogen generates the strong Jovian magnetic field (Jones, 2011(Jones, , 2014. In contrast to rocky bodies, Jupiter does not have an abrupt change between its metallic hydrogen (magnetic source) and molecular hydrogen (source free) regions. The change is expected to be gradual. The electrical conductivity profile of the different hydrogen layers at different depths from an ab-initio simulation (French et al., 2012) does not indicate a clear value of the dynamo region radius. Previous attempts to constrain this radius using the magnetic energy spectrum place it somewhere between 0.80 and 0.90

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

“…The flow is dominated by an equatorial jet, which induces intense secular variation in the vicinity of the Great Blue Spot (the region of concentrated field at the equator) as the magnetic field associated with this spot is swept eastwards. Owing to its dominant role in generating the secular variation [1][2][3]12 , a recent set of orbits by the Juno spacecraft 13 was targeted at this region.…”

Mantle-driven north–south dichotomy in geomagnetic polar minima

“…The absence of substantial polar minima at Mercury's field is likely due to the presence of a thick stratified layer at the top of the core (Christensen, 2006) that diffuses small-scale field features such as the polar minima (Olson et al, 2017). In contrast, the magnetic field of Jupiter (Sharan et al, 2022) exhibits significantly stronger polar minima than Earth's (Table 1). Fig.…”

Dynamo Simulations of Jupiter's Magnetic Field: The Role of Stable Stratification and a Dilute Core

“…This is based on geometric reasoning: the further one is from the source generating region, the more strongly higher order terms in the potential field expansion will decay relative to lower order terms (i.e., "all things resemble a dipole when observed from a far enough distance", see Equation 21). Using this method on Juno-derived magnetic field models, one would estimate that Jupiter's convective dynamo extends to between 0.81 and 0.85 R J (Connerney et al, 2018(Connerney et al, , 2021Sharan et al, 2022).…”