Advances in mesoscale modeling of katabatic flows over large ice sheets

On going work in the area of mesoscale modeling over large ice sheets during the last decade has highlighted numerous shortcomings in model simulations in the polar regions, including boundary layer and cloud / radiation processes. Significant changes in the model parameterizations, that address some of the known problems, have recently been incorporated into a highly modified version of the Penn State / National Center for Atmospheric Research fifth generation mesoscale model (MM5), referred to as Polar MM5.

Results from two years of simulations with the Polar MM5 over the Antarctic and Greenland ice sheets will be presented. Model verification using arrays of automatic weather stations over both ice sheets indicates substantial skill in predicting near surface winds, temperature, pressure, and surface energy budgets. The vertical structure of the katabatic layer (including the depth of the layer, height and strength of the katabatic jet, and temperature profile) have been verified using aircraft data collected during the KABEG'96 field campaign in Greenland.

Research and operational plans for the Polar MM5 will also be discussed. An operational version of the Polar MM5 was used during the second half of the 1999 / 2000 Antarctic field season in support of the United States Antarctic Program operations. Plans for continued used of Polar MM5 as an operation model will be discussed. Also, work on a climate version of Polar MM5 will be described.