[GTP] Joint CGD GTp seminar-Corentin Herbert

[Carolyn Mueller]

Just a reminder of Monday's Seminar
> Joint CGD GTP Seminar
> Large-scale atmospheric flows predicted by statistical mechanics
> Corentin Herbert
> Laboratoire des Sciences du Climat et de l'Environnement
> Monday, December 12, 2011, Mesa Laboratory, Main Seminar Room, Lecture 
> at 3:30



> Two-dimensional turbulent flows are known to develop large-scale 
> coherent structures which can be explained and predicted by 
> statistical mechanics in a relatively satisfactory way. Given a small 
> set of macroscopic quantities (energy, circulation, enstrophy...); it 
> is possible to compute the equilibrium state ultimately reached by the 
> flow. Phase diagrams classifying the different flow structures 
> obtained for the different values of the macroscopic parameters can be 
> constructed. Applying this theory to a simple model of the atmosphere 
> (the quasi-geotrophic equations on a rotating sphere), I shall show 
> that in the absence of a bottom topography, the statistical 
> equilibrium states are only purely zonal, solid-body rotations, and 
> symmetry-breaking dipolar flows. In this case, the phase diagram 
> displays a second-order phase transitions between these two equilibria 
> for a critical value of the energy. When a bottom topography is added, 
> we obtain other possibilities reminiscent of the atmosphere of the 
> Earth. Although these new states are formally unstable in the 
> statistical mechanics framework, they may be long-lived in practice 
> and thus relevant for atmospheric modelling. I will also discuss the 
> puzzling thermodynamic properties of the statistical equilibria 
> (negative statistical temperatures, vanishing specific heat, 
> non-concave microcanonical entropy...) in relation with the general 
> problem of statistical mechanics of systems with long-range interaction.
>
>
> https://gtp.ucar.edu/events/large-scale-atmospheric-flows-predicted-statistical-mechanics 
>
>