Self-consistent Predictions of the Gravity and Magnetic Fields to be Measured by Juno at Jupiter

Abstract:

Our dynamo simulations of Jupiter solve for the three-dimensional time-dependent gravity field, magnetic field, and zonal winds, all self-consistently maintained by the rotating thermal convection in the model's density-stratified and electrical-conductivity-stratified interior. The radial and latitudinal components of the perturbation gravitational acceleration, due to density perturbations throughout the interior and to surface deformations, have latitudinally banded structures at Juno's orbital perijove, 1.07 R from Jupiter's center (R = Jupiter's radius). Likewise, the radial and latitudinal components of the magnetic field, generated deep below the surface, have latitudinally banded structures at perijove. However, neither field displays multiple narrow bands at high latitude when the model's convection zone extends down to a core of radius 0.1 R. The banded patterns are effectively gone at and beyond 3 R, leaving a dominantly dipolar pattern in the magnetic field. The longitudinal components of the gravity and magnetic fields at perijove are much smaller in amplitude, much less axisymmetric, and much more time-dependent. Our simulations suggest that, if latitudinally banded patterns in the gravity and magnetic fields are detected by NASA's Juno spacecraft, the strong zonal winds observed on Jupiter likely extend to a significant depth below the surface where the mass density and electrical conductivity are much greater than they are at the surface. On the other hand, no banded structures in these fields detected by Juno would suggest that the zonal winds on Jupiter are likely shallow atmospheric features.