Effects of parameterized diffusion on simulated hurricanes

It is shown that the boundary layer in these simulations is consistent with known analytical solutions in that boundary layer depth increases and the amount of "overshoot" (maximum wind in excess of the gradient wind) decreases with increasing vertical diffusion. However, the maximum wind itself depends mainly on horizontal diffusion and is relatively insensitive to vertical diffusion; the overshoot variation with vertical viscosity mainly comes from changes in the gradient wind with vertical viscosity.

The present considerations of parameterized diffusion allow a new contribution to the dialog in the literature on the meaning and interpretation of the Emanuel potential intensity theory.