Tip Jets and Barrier Winds A QuikSCAT Climatology of High Wind Speed Events around Greenland

• Published in: Journal of climate Vol. 18; no. 18; pp. 3713 - 3725
• Main Authors: Moore, G. W. K., Renfrew, I. A.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 15.09.2005
• Subjects: Acceleration; Barrier winds; Case studies; Climate; Climatology; Coasts; Conservation; Cyclones; Datasets; Earth, ocean, space; Exact sciences and technology; External geophysics; Froude number; General circulation. Atmospheric waves; Gradient winds; Jets; Meteorological satellites; Meteorology; Meteors; Oceans; Parting phrases; Scatterometers; Seas; Severe weather; Spatial discrimination; Spatial resolution; Surface wind; Topography; Weather; Wind; Wind speed; Wind velocity; Winds; Arctic region; North Atlantic; Greenland; Antarctic Peninsula; Northern Hemisphere; Labrador Sea; ANE, Greenland, Oestgroenland; ANE, Atlantic, Denmark Strait; AN, Greenland; Wind field; Marine atmosphere; Atlantic Ocean; Space remote sensing; topography; Satellite observation; Scatterometer; Coastal zone; Air flow; Synoptic scale; Winter; Severe weather; Jet stream; Marine meteorology; Orography; QuikSCAT satellite; polar regions; Geostrophic wind; atmospheric circulation; Surface wind; Composite analysis
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli3455.1

The high topography of Greenland results in a number of orographically induced high wind speed flows along its coast that are of interest from both a severe weather and climate perspective. Here the surface wind field dataset from the NASA–JPL SeaWinds scatterometer on board the Quick Scatterometer (Quik-SCAT) satellite is used to develop a wintertime climatology of these flows. The high spatial resolution and the twice-daily sampling of the SeaWinds instrument allows for a much more detailed view of the surface winds around Greenland than has been previously possible. Three phenomena stand out as the most distinctive features of the surface wind field during the winter months: the previously identified tip jets and reverse tip jets, as well as the hitherto unrecognized barrier flows along its southeast coast in the vicinity of the Denmark Strait. Peak surface wind speeds associated with these phenomena can be as large as 50 m s−1with winds over 25 m s−1occurring approximately 10%–15% of the time at each location. A compositing technique is used to show that each type of flow is the result of an interaction between a synoptic-scale parent cyclone and the high topography of Greenland. In keeping with previous work, it is argued that tip jets are caused by a combination of conservation of the Bernoulli function during orographic descent and acceleration due to flow splitting as stable air passes around Cape Farewell, while barrier winds are a geostrophic response to stable air being forced against high topography. It is proposed that reverse tip jets occur when barrier winds reach the end of the topographic barrier and move from a geostrophic to a gradient wind balance, becoming supergeostrophic as a result of their anticyclonic curvature.