Oscillations and Stability of the Jupiter Polar Cyclones

Abstract

Juno discovered the circumpolar cyclones polygons on Jupiter in 2017. Fundamental questions regarding Jovian cyclogenesis concern the formation mechanism and whether these cyclones are deep or shallow. Recent data by Juno/JIRAM infrared camera show that any change is an extremely unlikely event on an annual scale. Only once, in 2019, a sixth cyclone joined the pentagonal structure in the South, but it disappeared after 2 months without merging with the pre-existing cyclones; disappearance or creation of stable cyclones has never been observed. Additionally, the rotation speeds of the north and south polygons as a whole are not compatible with the shallow hypothesis; both structures drift at a much smaller rate than the typical scale velocities on Jupiter surface, and differ at the two poles. Cyclones oscillate around what may seem like equilibrium positions, and these oscillations tend to propagate from one cyclone to another. These oscillations have almost equal timescales, and here we investigate the possible implications of such similarity.