Winter time flow over and around Greenland: trajectories related to torques

Abstract

Results of first steps towards a dynamically oriented climatology of winter time flow over and around Greenland are presented. The synoptic situations in the Greenland area are classified with respect to Greenland’s axial mountain torque. This torque is positive (negative) if the surface pressure at the eastern slope is higher (lower) than at the windward side. Mean trajectories are calculated from correlations of observed flows with the torque. Three classes of trajectories are formed: ‘blocked’, ‘over’ and ‘around’. It is found for low-level starting points west of Greenland, that blocked trajectories are most common for positive torques while the bulk of the trajectories is deflected around Greenland or crosses the massif for negative torques. These results are shown to be broadly consistent with the standard non-dimensional height criterion. Flow splitting is common to the west of Greenland. Stagnation points are found west of Greenland but also above the eastern slopes. Tip jets occur for negative torque events only.