WINTERTIME SURFACE WINDS OVER THE GREENLAND ICE-SHEET

Clear-sky, wintertime surface winds over the Greenland Ice Sheet are s imulated with a three-dimensional mesoscale numerical model. It is sho wn 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 lo ngwave radiational cooling of the sloping ice terrain is the key drivi ng force of this cold airflow. In some coastal areas the downslope win ds converge into large fjords, such as Kangerlussuaq and Sermilik. Thi s is consistent with the frequent presence in these areas of warm sign atures on cloud-free thermal infrared satellite images that are genera ted by katabatic winds. The shape of the Greenland Ice Sheet plays an important role in directing the Row of the surface winds. The study de monstrates that the surface wind pattern is only moderately affected b y climatological flow around and over the ice sheet. The mass redistri bution associated with the katabatic wind circulation plays an importa nt role in generating prominent features of the time-averaged sea leve l pressure and upper-level circulation fields near Greenland.