Mesoscale energy spectra of moist baroclinic waves

Dry baroclinic waves yield upper-tropospheric kinetic energy spectra that resemble a -3 power law. Decomposition into horizontally rotational and divergent kinetic energy shows that the divergent energy has a much shallower spectrum, but its amplitude is too small to yield a characteristic kink in the total spectrum, which is dominated by the rotational part.

The inclusion of moist processes energizes the mesoscale. In the upper troposphere, the effect is mainly in the divergent part of the kinetic energy; the spectral slope remains shallow (around -5/3) as in the dry case, but the amplitude increases with increasing humidity. The divergence field in physical space is consistent with inertia-gravity waves being generated in regions of latent heating and propagating throughout the baroclinic wave.