[GTP] Joint MMM GTp seminar-Freddy Bouchet

[Silvia Gentile]

Joint GTP MMM Seminar

Equilibrium and Out of Equilibrium Phase Transitions for Two Dimensional 
and Geostrophic Turbulence
Freddy Bouchet
INLN-CNRS Nice and CNLS Los Alamos

The equilibrium statistical mechanics of two dimensional and geostrophic 
flows (Robert-Sommeria-Miller theory), predicts the outcome for the 
large scales of the flow, resulting from the turbulent mixing. We 
describe applications of this theory to describe detailed properties of 
the Great Red Spot and other localized structures of Jupiter's 
troposphere. It explains the detailed ring structure and stability of 
the Great Red Spot velocity field.
Another aim of this talk is to discuss the range of applicability of 
this theory to ocean dynamics. This range is probably limited due the 
inertial assumption underlying this equilibrium approach. Still we will 
show that the theory is able to reproduce in much detail localized 
structures like the gulf stream rings. We also uncover the relations 
between strong eastward mid-basin inertial jets, like the Kuroshio 
extension and the Gulf Stream, and statistical equilibria. All these 
results cannot be obtained in the context of the older Salmon-Kraichnan 
theory, that mainly predicts only features related to the topography.
Forcing and dissipation play an essential role for ocean dynamics. We 
consider an out of equilibrium theory of the mixing of the potential 
vorticity that takes these into account. We describe results for 
ergodicity in this out of equilibrium configuration. We also show that 
we can predict out of equilibrium phase transitions, where the flow 
switches randomly between two different large scale patterns. The main 
interest of the theory is to predict the range of parameters of this 
bistability phenomena and to predict the mean streamfunction for each of 
these two states. We discuss possible future applications of these ideas 
to the bistability of the Kuroshio Current, and of other geophysical flows.
We will also describe briefly recent results of the asymptotic behavior 
of the 2D Euler equation and results on the 2D Euler equation with 
stochastic forces.


October 8, 2009
Foothills Laboratory 2
Room 1022
Lecture 3:30pm