Quantitative stability of the Rossby--Haurwitz waves of degree two for the Euler equation on ${\mathbb{S}}^2$

Matias G. Delgadino, Luca Melzi

We show that the degree-2 Rossby--Haurwitz travelling waves on the Euler equation on ${\mathbb{S}}^2$ are orbitally stable. Our proof is short, quantitative, and conceptually easy to…