First results of applying the updated two-energies turbulence scheme over complex terrain

Abstract

The unified parameterization of turbulence and clouds in the atmospheric boundary layer is one of the challenges in current weather and climate models. The updated two-energy turbulence scheme is able to successfully model both stratocumulus cases and shallow convection without the need of an additional parameterization for non-local fluxes. The update includes the introduction of the entropy potential temperature to distinguish between a shallow convection and a stratocumulus regime. In addition, the two-energy scheme is coupled to a simplified assumed PDF method in order to achieve a more universal representation of the cloudy regimes. The updated turbulence scheme has been tuned based on several idealized cases and is now evaluated for several real cases in the ICON modeling framework. These cases include cloud streets over relatively flat terrain and stable boundary layers including fog over complex terrain. The performance of the updated scheme is comparable to or better than the operational setup, and can be thus used instead of the operational turbulence and shallow convection scheme in ICON.