Large wind shears and their implications for diffusion in regions with enhanced static stability: The mesopause and the tropopause

In these regions, the static stability also reaches peak values and therefore allows large vertical shears before the onset of dynamical instability.

The wind shear peaks near the mesopause and the tropopause from the simulation compare well with those identified in observations, including the magnitude, latitudinal dependence, and large shear statistics. By analyzing the probability density functions of the wind shears and their dependence on the zonal scales, it is found that smaller scale processes, likely gravity waves, contribute significantly to the large shears and may play a dominant role in producing the largest shears.