The Oscillatory Motion of Jupiter's Polar Cyclones Results From Vorticity Dynamics

Nimrod Gavriel and Yohai Kaspi

Submitted on 1 September 2022


The polar cyclone at Jupiter's south pole and the five cyclones surrounding it oscillate in position and interact. These cyclones, observed since 2016 by NASA's Juno mission, present a unique opportunity to study vortex dynamics and interactions on long time scales. The cyclones' position data, acquired by Juno's JIRAM instrument, is analyzed, showing dominant oscillations with ~12 month periods and amplitudes of ~400 km. Here, the mechanism driving these oscillations is revealed by considering vorticity-gradient forces generated by mutual interactions between the cyclones and the latitudinal variation in planetary vorticity. Data-driven estimation of these forces exhibits a high correlation with the measured acceleration of the cyclones. To further test this mechanism, a model is constructed, simulating how cyclones subject to these forces exhibit similar oscillatory motion.


Comment: 9 pages, 5 figures, 11 supplementary pages, 9 supplementary figures

Subjects: Astrophysics - Earth and Planetary Astrophysics; Physics - Atmospheric and Oceanic Physics; Physics - Geophysics