EGU25-12975, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-12975
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
A mechanism for equatorial jet formation on ice giants
Keren Duer-Milner1,2,3, Nimrod Gavriel1, Eli Galanti1, Eli Tziperman4,5, and Yohai Kaspi1
Keren Duer-Milner et al.
  • 1Weizmann Institute of Science, Rehovot, Israel (kerenduer89@gmail.com)
  • 2Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden, the Netherlands
  • 3SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA, Leiden, the Netherlands
  • 4Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts
  • 5School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
The equatorial jets observed on the Jovian planets - Jupiter, Saturn, Uranus, and Neptune - exhibit extreme equatorial zonal flow patterns, manifesting as either strongly prograde (in the gas giants) or strongly retrograde (in the ice giants). Existing theories have often treated gas giants and ice giants separately, primarily focusing on the differences between deep and shallow dynamics. However, recent gravity measurements suggest that the convective envelope of Jupiter may be similar to those of the ice giants, challenging the traditional distinctions between these planet types.
We present results from a numerical simulation that introduces a mechanism capable of explaining the equatorial jets on the ice giants in a manner analogous to those on the gas giants. In these simulations, as shown theoretically by Busse et al., the convective dynamics and planetary rotation drive the formation of tilted convection columns. These columns, extending cylindrically from the deep interior to the outer atmospheric layers, play a crucial role in shaping the zonal wind patterns. In this study, the tilting of the convection columns introduces asymmetries in momentum transport, leading to a bifurcation of the flow into either superrotation (prograde jets) or subrotation (retrograde jets).
Through a detailed analysis of the convection-driven columnar structures, we demonstrate that the equatorial wave properties and the leading-order momentum balance share remarkable similarities between the two types of solutions. Our findings comprehensively explain the potential for both superrotation and subrotation solutions under constant physical conditions, thereby potentially explaining the diverse zonal wind patterns observed on the Jovian planets and providing a deeper understanding of the mechanisms driving equatorial jet formation.

How to cite: Duer-Milner, K., Gavriel, N., Galanti, E., Tziperman, E., and Kaspi, Y.: A mechanism for equatorial jet formation on ice giants, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12975, https://doi.org/10.5194/egusphere-egu25-12975, 2025.