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

Abstract

A B S T R A C T 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.

An easterly tip jet off Cape Farewell, Greenland. I: Aircraft observations

“…Almost all previous studies have relied exclusively on either satellite-based observations, such as scatterometer winds (e.g. QuikSCAT winds: Moore and Renfrew, 2005;Sampe and Xie, 2007), meteorological analyses or reanalyses (Moore, 2003;Egger, 2006), or numerical weather prediction (NWP) simulations (Doyle and Shapiro, 1999;Petersen et al, 2003Petersen et al, , 2005Orr et al, 2005;Martin and Moore, 2007;Ohigashi and Moore, 2009). The only exceptions are two recent studies that jets'; here we use the adjective 'easterly' in preference to 'reverse' tip jet.…”