- Antoine Venaille: LEGI, UJF, INPG, CNRS, BP 53, 38041 Grenoble, France and INLN, CNRS, UNSA, 1361 route des lucioles, 06 560 Valbonne-Sophia Antipolis, France.
A theoretical description for the equilibrium states of a large class of models of two-dimensional and geophysical flows is presented. A statistical ensemble equivalence is found to exist generically in these models, related to the occurrence of peculiar phase transitions in the flow topology. The first example of a bicritical point (a bifurcation from a first toward two second order phase transitions) in the context of systems with long-range interactions is reported. Academic ocean models, the Fofonoff flows, are studied in the perspective of these results.