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What controls atmospheric and oceanic motions on planetary scales ?


IPGP - Îlot Cuvier


Séminaires thème Intérieurs de la Terre et des planètes

Salle 310

Simon Cabanes

Sapienza - Università di Roma

Zoom link: Meeting ID : 553 965 6418 Password : 555186 Within our solar system, substantial atmospheres and oceans are found on a series of planetary bodies: The Earth, Venus, Mars and the gas giants, i.e. Jupiter, Saturn, Neptune. All these planets show the formation of zonal jets, i.e. bands of east-west directed flows, which are the most energetic features that fundamentally structure atmospheric and oceanic circulations on a planetary scale, see Figure 1. Zonal jets are known to play a critical role in the organization of the climatic system by transporting essential substances, such as heat, humidity, gases and nutrients, around the planet. An understanding of the physical ingredients controlling the formation of these planetary jets is a prerequisite to our understanding of climate variability, for both past and future climate changes. So far, it has been accepted that the energetic strength of the zonal jets is directly related to the transformation of solar energy into sources of flow motion within the atmosphere. This assertion, however, disregards a fundamental conundrum formulated 20 years ago by Ingersoll et al. (2004), why are zonal jets on Jupiter 4 times stronger of that on Earth while Jupiter receives 30 times less of solar energy?; these facts seem to contradict each other. Thanks to the project the JUpiter Modeling Platform (JUMP), we conducted an in-depth analysis of gas giants’ zonal jets emulated from numerical and laboratory simulation as well as from direct imaging of the planets and we offered a partial answer to this conundrum. We showed that the strength of the jets is set by the « Rotational Kinetic Energy » of the planet rather than solar energy input.