Wintertime Surface Winds over the Greenland Ice Sheet

Abstract

Clear-sky, wintertime surface winds over the Greenland Ice Sheet are simulated with a three-dimensional mesoscale numerical model. It is shown that the simulated winds blow from the broad gently sloped interior to the steep coastal margins. This general wind pattern is similar to that found over Antarctica due to the same governing dynamics. The longwave radiational cooling of the sloping ice terrain is the key driving force of this cold airflow. In some coastal areas the downslope winds converge into large fjords, such as Kangerlussuaq and Sermilik. This is consistent with the frequent presence in these areas of warm signatures on cloud-free thermal infrared satellite images that are generated by katabatic winds. The shape of the Greenland Ice Sheet plays an important role in directing the flow of the surface winds. The study demonstrates that the surface wind pattern is only moderately affected by climatological flow around and over the ice sheet. The mass redistribution associated with the katabatic wind circulation plays an important role in generating prominent features of the time-averaged sea level pressure and upper-level circulation fields near Greenland.