Parameterization of large-scale turbulent diffusion in the presence of both well-mixed and weakly mixed patchy layers

We show that it is the largest, most vigorous and less common turbulent layers that make the major contribution to global diffusion. Finally, we make estimates of global-scale diffusion coefficients in the lower stratosphere and upper troposphere. For the lower stratosphere, κeff ≈ 2x10−2 m2 s−1, assuming no other processes contribute to large-scale diffusion.