On the variability of Saturn's equatorial jet at cloud top level

Abstract

Saturn's Equatorial jet is apparently highly variable in wind speed at the upper cloud level with changes, between 1980-81 and 1994-2004, amounting up to a 40% in its peak value. However, there is some controversy if this is a real change in the winds or an effect due to clouds placed at different altitude levels where a vertical wind shear is present. In a recent study of cloud altitudes we have shown that vertical shears alone cannot account for the 200 ms^-1 velocity change observed between both periods. Here, we reinforce this hypothesis based on simple dynamical calculations and discuss possible phenomena that can be involved in such variability.