Abstract : 2G.6
Comparison of the Prandtl model with K(z) and non-zero f with Doppler sodar observations

Iva Kavcic, Branko Grisogono, Ian A. Renfrew, Philip S. Anderson, Zeljko Vecenaj, Ivana Stiperski
Department of Geophysics, Faculty of Science, University of Zagreb, Croatia

Katabatic flows are regular features of stable boundary layers which are not usually well represented in climate and even some weather prediction models (due to the need for a sufficient vertical resolution). The solutions for (U, V, Theta) from the recently extended analytical 1D Prandtl model are verified against observations (the 15-min averages) from a novel autonomous Doppler sodar wind profiling system. Two sodar settings were used: high vertical resolution with frequency=502Hz, range gates~10-70m, height~20-500m, and standard vertical resolution with frequency=506Hz, range gates~20-60m, height~20-500m. The emphasis is put on the height and intensity of the inversion, and the height and speed of low-level jet. Both the analytical model assumptions and the related soundings over the wintertime Antarctica correspond to “primarily katabatic driven” flows where the influence from larger-scale weather systems is reduced. The comparison between the analytical model and the data reveals both the strength and drawbacks of the extended Prandtl model. Therefore, 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.