A climatology of wintertime barrier winds off southeast Greenland

A climatology of barrier winds along the southeast coast of Greenland is presented based on 20 years of winter months (1989-2008) from the ECMWF reanalysis product ERA-Interim. Barrier winds are low-level, strong wind jets which form when air is forced towards a steep and high topographic barrier such as Greenland. Unable to ascend the barrier presented to the flow, the air is dammed and forced along the coast in a strong coastal jet.

The reason why the study of barrier winds off Greenland could be particularly important is that the region is key for the ocean's thermohaline circulation. There is evidence that other strong, intermittent wind features are affecting ocean circulation in the region. For example, the westerly Tip Jets that occur around Cape Farewell have been shown to force deep convection in the Irminger Sea. By putting an emphasis on the surface fluxes of heat and momentum it is hope this climatology will form a useful tool for the study of wind driven processes in the region.

Barrier winds were found to occur on average once a week in the winter months, but the typical surface fluxes (especially heat) varied widely between events (between 0 and 600 W m^-2, area averaged), the result of vastly different low-level temperature regimes. Warmer barrier winds developed when there was a blocking high pressure over the Nordic Seas, while colder barrier winds owe their presence to a train of cyclones through the region. The conclusion is that knowledge of the wider synoptic environment is vital in determining the local patterns and strength of surface fluxes.