The familiar axisymmetric zones and belts that characterize Jupiter’s weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes1. Two-dimensional turbulence in combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows2. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur3,4. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles5,6,7,8,9. Jovian polar regions are not visible from Earth owing to Jupiter’s low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter’s equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn’s polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.
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The JIRAM project is founded by the Italian Space Agency (ASI). In particular this work has been developed under the ASI-INAF agreement number 2016-23-H.0. The JunoCam instrument and its operations are funded by the National Aeronautics and Space Administration. A portion of this work was supported by NASA funds to the Jet Propulsion Laboratory, to the California Institute of Technology, and to the Southwest Research Institute. A.P.I. was supported by NASA funds to the Juno project and by NSF grant number 1411952.
Extended data figures
This zipped file contains 9 videos for the North Pole (8 CPC, plus the NPC); each video is made of 11 images. It also contains 6 videos for the South Pole (5 CPC, plus the SPC); each video is made of 6 images. References are to Figure 1. 0°W in System III is positioned on the right centre of the images. Both Poles are seen from above, namely, progressing counter clockwise you move towards east in the North and towards west in the South. For the North Pole videos, north0.avi.mp4 is the North Polar Cyclone, north1.avi.mp4 is the cyclone at 0°W and for the other videos north[X].avi.mp4, the numbering [X=2 to 8] proceeds counter clockwise. For the South Pole videos, south0.avi.mp4 is the South Polar Cyclone, south1.avi.mp4 is the cyclone at 150°W and for the other videos south [X].avi.mp4, the numbering [X=2 to 5] proceeds counterclockwise.
About this article
Physical Review Fluids (2019)