Thermocompositional Layers and Jupiter’s Gravity, Magnetic Field, and Supersolar Heavy Elements

Abstract Juno mission observations of Jupiter’s gravity, magnetism, and richly structured atmospheric flow point to complex interior structures. Traditional models of Jupiter’s interior, with one or two convecting layers and a compact core, do not plausibly satisfy the Juno gravity observations. This has opened the door to a new generation of interior models, a diversity of which satisfy the gravity data, that include nonadiabatic layering and dilute cores. In addition to nonuniqueness, Juno magnetic field observations indicating a deep dynamo, previous Galileo mission observations of atmospheric supersolar heavy-element abundances, and uncertainty regarding the prevalence of double-diffusive convection challenge the understanding of Jupiter’s structure and dynamics. Here I show, using thermodynamics, previous equation-of-state-derived radial properties, and Theory of Figures to seventh order that a new Jovian interior model with a dynamo below two thermocompositional layers satisfies the Juno and Galileo observations. Invoking marginal stability, which follows from considering slowly evolving composition, reduces nonuniqueness by constraining the location of model layer boundaries. The inner, compositionally stable layer is marginally stable to semiconvection and bounded above by an outer convective zone. The outer, thermally stable, atmospheric layer is marginally stable to fingering instability and supports an inverse Z -gradient. This preferred interior model is implemented as the background state for a dynamo simulation. The magnetic and flow fields and the gravity harmonic contributions that arise from zonal flow are comparable to those of Jupiter.