Computer simulations of Jupiter's deep internal dynamics help interpret what Juno sees.

We describe computer simulations of thermal convection and magnetic field generation in Jupiter's deep interior: that is, its convective dynamo. Results from three different simulations highlight the importance of including the dynamics in the very deep interior, although much of the convection and field generation seems to be confined to the upper part of the interior. A long-debated question is to what depth do Jupiter's zonal winds extend below its surface. Our simulations suggest that, if global latitudinally banded patterns in Jupiter's near-surface magnetic and gravity fields were detected by Juno, NASA's orbiting spacecraft at Jupiter [Bolton S, et al. (2017) Science 356:821-825], they would provide evidence for Jupiter's zonal winds extending deep below the surface. One of our simulations has also maintained, for a couple simulated years, a deep axisymmetric inertial wave, with properties at the surface that depend on the size of the model's small rocky core. If such a wave was detected on Jupiter's surface, its latitudes and oscillation frequency would provide evidence for the existence and size of Jupiter's rocky core.

Simulations of two-dimensional turbulent convection in a density-stratified fluid.

High resolution computer simulations of two-dimensional convection using the anelastic approximation are presented. These calculations span Rayleigh numbers from 10(8)-10(12) for Prandtl number equal to unity, with the fluid density decreasing by a factor of 12 from the bottom to the top of the convection region. This range covers several decades in the "hard" turbulent regime. While many studies of this sort have been conducted for the Boussinesq approximation (i.e., no density stratification), we use the anelastic approximation with a significant density stratification in this turbulent regime. The convection is dominated by a large-scale coherent flow composed of ascending and descending superplumes. We find a power law exponent of 0.28 for the Nusselt-Rayleigh number scaling and a power law with exponent of 0.50 for the Reynolds-Rayleigh number scaling for the entire parameter space studied. These values are very similar to those determined experimentally and analytically for convection with no density stratification.