| Abstract: Data from very high horizontal resolution simulations
with the Geophysical Fluid Dynamics Laboratory SKYHI general circulation
model are used to calculate the kinetic energy spectrum as a function of
horizontal wavenumber, k, in the upper troposphere. The spectrum
shows the familiar ~ -3 slope at scales longer than ~ 1000 km, in agreement
with previous general circulation model and observational studies. At shorter
scales, the spectrum becomes shallower with a slope ~ -5/3, also in agreement
with available observations. The -5/3 slope spans about a decade of the
resolved scales and this result represents the first successful simulation
of such a broad range of the mesoscale regime by a global model. Partitioning
of the flow between rotational and divergent components shows that the
rotational part dominates at large scales and that there is approximate
equipartition between rotational and divergent parts at mesoscales. Analysis
of the parameterized kinetic energy dissipation shows that vertical diffusion
dominates horizontal diffusion for a wide range of wavenumbers extending
well into the k-5/3 regime. |