A Hopf-bifurcation theorem for the critically dissipative   quasi-geostrophic equation
  This paper is devoted to the study of the dynamical behavior of the critically dissipative quasi-geostrophic equation in $\textbf{T}^2$. We prove that this system possesses time-dependent periodic solutions, bifurcating from a smooth steady solution, i.e. a Hopf-Bifurcation theorem. 
Weiping Yan and Yong Li
math.DS math.AP