  We explain the emergence and robustness of intense jets in highly turbulent
planetary atmospheres, like on Jupiter, by a general approach of statistical
mechanics of potential vorticity patches. The idea is that potential vorticity
mixing leads to the formation of a steady organized coarse grained flow,
corresponding to the statistical equilibrium state. Our starting point is the
quasi-geostrophic 1-1/2 layer model, and we consider the relevant limit of a
small Rossby radius of deformation. Then narrow jets are obtained, scaling like
the Rossby radius of deformation. These jets can be either zonal, or closed
into a ring bounding a vortex. Taking into account the effect of the beta
effect and a sublayer deep shear flow, we predict an organization of the
turbulent atmospheric layer into an oval-shaped vortex amidst a background
shear. Such an isolated vortex is centered over an extremum of the equivalent
topography (determined by the deep shear flow and beta-effect). This prediction
is in agreement with analysis of wind data in major Jovian vortices (Great Red
Spot and Oval BC).
