engleski

"Comparison of the rotating Prandtl model with K(z) and a mesoscale numerical model"

Deployed analytical approach extends Prandtl model for simple katabatic flow by using vertically varying eddy diffusivity and allowing for the Earth rotation. The related flow pertains to long glaciers on Greenland and Antarctic, which are poorly resolved in climate and some numerical weather prediction (NWP) models. We compare the extended 1D analytical Prandtl model for (U, V, Theta) with a mesoscale numerical model. The MIUU mesoscale model employs a fine vertical resolution and a higher-order turbulence parameterization scheme. The analytical model slightly underestimates both the height and the speed of U maximum, and the variations in Theta However, it successfully describes the time evolution of the V component and its maximum, although somewhat overestimating the magnitude of V. Nevertheless, the overall tentative agreement of the analytical model with the MIUU model profiles is good. The differences arise from the hierarchy of the effects of the various assumptions made in the extended analytical Prandtl model. Hence, further improvements of the Prandtl model will be amendable as well as recommendations for a better parameterization of katabatic flows in large-scale numerical models.

Stable boundary layer; Prandtl model; MIUU model

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