Two-dimensional turbulence on the surface of a rotating sphere develops strong spectral anisotropy. In the inverse-cascade range with stochastic small-scale forcing, the spectral slopes at larger scales are shown to be significantly different in different sectors of the wavenumber plane. A steep -5 slope emerges in the sector closest to the zonal axis, while far away from the zonal axis, the -5/3 Kolmogorov law prevails. The -5 spectrum agrees with Rhines' prediction for geostrophic turbulence that assumes that the large scale energy spectrum depends only on the local wave number and beta. The presented high-resolution simulations on the surface of the rotating sphere are fully consistent with our previous simulations conducted in a periodic box on the beta-plane.
Close window or click on previous window to return to the Conference Program.
12th Conference on Atmospheric and Oceanic Fluid Dynamics