Roughly speaking, superrotation occurs when the atmosphere of a planet goes round faster than the planet itself. In practice this means that the zonal flow at the equator is prograde, or eastward. Earth’s atmosphere does not normally superrotate, whereas the atmospheres on Venus, Titan, Jupiter, Saturn and many tidally-locked exo-planets do. Superrotation is somewhat surprising because it suggests an upgradient (or ‘antidiffusive’) transfer of angular momentum.

I will first review the various mechanisms that might give rise to superrotation in both deep and shallow atmospheres, and then present a unified view of superrotation in tidally-locked and slowly-rotating shallow atmospheres.

Geoffrey Vallis est professeur au Département de Mathématiques de l’Université d’Exeter. C’est un grand spécialiste de la mécanique des fluides géophysiques, de la circulation des atmosphères planétaires, de la dynamique océanique et climatique.

Lieu
Sorbonne Université
Campus Pierre et Marie Curie
4, place Jussieu 75005 PARIS
Amphithéâtre Charpak
Rez-de-Chaussée/Saint-Bernard, accès par la tour 22

Visio
https://cnrs.zoom.us/j/96498910932?pwd=bicIyCab0ciynuzXwBJ4hjpvnmWa9v.1