Lessons from Juno & Cassini: linking atmosphere and interior of Jupiter and Saturn

Presenter: Tristan GUILLOT
In orbit since July 2016, Juno is changing the way we see Jupiter but also the other giant planets. The measurements of the gravity field of the planet have allowed to probe the deep interior in several ways. It allowed for the first time to constrain the depth of the planet’s zonal jets to about 3000km below the clouds and led to new interior models including the presence of a dilute core and a still unsolved interior structure. Similar measurements by Cassini led to a constraint on the depth of Saturn’s zonal flow, about 9000km, in agreement with the Juno results for Jupiter. Differential rotation in the interior is suppressed where hydrogen becomes conductive enough to be dragged by the giant planets' powerful magnetic fields.

In addition, Juno’s microwave radiometer show that, in Jupiter, ammonia, but probably also temperature are not as uniform as one expected, down to pressures of tens of bars. I will show that this may be explained by the interaction of water storms with ammonia, leading to a non-uniform and variable distribution of abundances and temperatures both vertically and latitudinally. The implications could be far-reaching for the understanding of giant planets dynamics and interiors.