Recipe for a Saturn-like Dynamo Model

The Cassini Grand Finale magnetic data at Saturn can be modeled with a perfectly axisymmetric spherical harmonic fit up to degree 11. This perfect axisymmetry is problematic because Cowling's Theorem states that such a field cannot be maintained by dynamo action.

One possible way to resolve this dilemma is for a mechanism to attenuate the field outside the dynamo region so that a non-axisymmetric field in the dynamo source region appears axisymmetric outside the surface. Previous work has typically appealed to the presence of a stably-stratified layer at the top of Saturn's dynamo region for this mechanism.

Here we use numerical dynamo models to search for possible ingredients such as stably stratified layers and various heat flux patterns on top of the dynamo region to produce a "Saturn-like" surface magnetic field. We evaluate the level of resemblance of a modeled field to Saturn's surface magnetic field through different aspects including: the dipole tilt, the sign and magnitude of the individual Gauss coefficients, and the ratio of non-axisymmetric to axisymmetric field. Using these characteristics of the magnetic field, we may be able to constrain properties of the deep interior of Saturn.