The axisymmetric circulation is that shown in Figure 3a of Schneider (2006); the statistically steady state of the macroturbulent circulation is that shown in Figure 3d. As in Schneider (2006), the upper left panel of the animation shows zonal-mean potential temperature (cyan, contour interval 10 K) and zonal wind (magenta, contour interval 4 m/s); the upper right panel shows the mean meridional streamfunction (magenta, contour interval 20 x 10^9 kg/s) and zonal-mean angular momentum (cyan, contour interval 0.1Ω a^2). The lower panel shows surface air temperature, with the zonal mean in the panel on the right.
In the macroturbulent simulation, there is no subgrid-scale diffusion of heat or momentum above the planetary boundary layer. Vertical subgrid-scale diffusion of heat and momentum is necessary for stability in the axisymmetric simulations. Because the subgrid-scale diffusion is turned off when the three-dimensional perturbation is added to the axisymmetric circulation, the Hadley circulation first weakens before it strengthens when large-scale eddies form.
Reference: Schneider, T., 2006: The general circulation of the atmosphere. Annual Reviews of Earth and Planetary Sciences, 34, 655-688.
