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Some recent findings about very stable boundary layers

The focus of this short talk is on two recent results related to strongly stable ABL. First and more elaborated part here is katabatic flow over long cool slopes. Since it was verified that classical scaling via Monin-Obukhov length performs over such slopes rather poorly, a modified Prandtl model is used instead. This linear analytic 1D model is extended for 1.) almost any gradual eddy diffusivity K(z) via the WKB method, and 2.) it includes the Coriolis effect. The result agrees well with the MIUU numerical mesoscale model ; moreover, it can be useful in parameterizing shallow persistent katabatic flows in NWP and climate models and in data interpretation. Second part relates only to numerical modeling with the concept of total turbulent energy parameterization. This promising approach appears suitable for modeling stable ABL, when compared to data and various LES, because it allows for turbulence at high Richardson number.

Strongly stable ABL; Katabatic flow; Prandtl model; WKB method

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