A Comprehensive Physical Parameterization of Diffusion for Whole Atmosphere Modeling

We describe the development and implementation of a data- and physics-based parameterization for diffusion that incorporates multiple internal sources of mixing throughout the whole atmosphere from ground to space. Alongside typical large-scale mixing dependent on Richardson number, we have introduced turbulent mixing due to parameterized non-orographic gravity wave breaking throughout the atmosphere and mixing in the thermosphere from molecular viscosity and heat conductivity. We focus on the thermospheric aspect of this parameterization as it is an integral part of Navy models that have been recently extended to forecast from the surface to 500 km altitude. Our combination of these processes into a single scheme naturally produces expected Reynolds number regimes throughout the atmosphere, including a laminar stratosphere and a turbopause. The parameterized diffusivities are suited for existing column-based vertical mixing schemes under the standard assumption of first-order closure, and we also explore their application within a new horizontal mixing scheme.