Abstract : 1A.1
Comparison of the rotating Prandtl model with K(z) and a mesoscale numerical model

Iva Kavcic, Ivana Stiperski, Branko Grisogono, Dale Durran
Department of Geophysics, Faculty of Science, University of Zagreb

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 weather models. Since it is difficult to obtain suitable observations having detailed vertical profiles (dz~10m, through ~300m depth) of the flow fields over the mentioned areas, we compare the extended 1D analytical model for (U,V,Theta) with a mesoscale numerical model. The mesoscale model employs a fine vertical resolution and a higher-order turbulence parameterization scheme. The comparison between the analytical and numerical model indicates good and weak sides of the extended Prandtl model; it also yields the hierarchy of the effects of the various assumptions made in this analytic 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.