The Forcing of Antarctic Katabatic Winds

Abstract

The temporal and spatial development of katabatic winds along an idealized slope representative of Anmtarctic terrain is examined using a hydrostatic, two-dimensional primitive equation model with explicit longwave radiation parameterization. A detailed diagnosis is made of a simulation in which katabatic flow develops from rest due to the strong radiational cooling of the underlying surface. Significant thermodynamic and dynamic differences are seen between the gravity-driven flows over the gently-sloping interior and over the steep ice slopes near the coast. The strongest temperature inversions and largest static stabilities are found over the interior of the continent, although the net cooling of the katabatic layer and magnitude of the downslope-directed horizontal pressure gradient force are greatest at the coast. The interior is characterized by low Rossby number, quasi-geostrophic type flows, while more intense, near-antitriptic winds occur at the coast. Model results are in reasonable agreement with the limited Antarctic observations.