A Climatology of Wintertime Barrier Winds off Southeast Greenland

Abstract

A climatology of barrier winds along the southeastern coast of Greenland is presented based on 20 yr of winter months (1989–2008) from the ECMWF Interim Reanalysis (ERA-Interim). Barrier wind events occur predominantly at two locations: Denmark Strait North (DSN; 67.7°N, 25.3°W) and Denmark Strait South (DSS; 64.9°N, 35.9°W). Events stronger than 20 m s−1 occur on average once per week during winter with considerable interannual variability—from 7 to 20 events per winter. The monthly frequency of barrier wind events correlates with the monthly North Atlantic oscillation (NAO) index with a correlation coefficient of 0.57 (0.31) at DSN (DSS). The associated total turbulent heat fluxes for barrier wind events (area averaged) were typically about 200 W m−2 with peak values of 400 W m−2 common in smaller regions. Area-averaged surface stresses were typically between 0.5 and 1 N m−2. Total precipitation rates were larger at DSS than DSN, both typically less than 1 mm h−1. The total turbulent heat fluxes were shown to have a large range as a result of a large range in 2-m air temperature. Two classes of barrier winds—warm and cold—were investigated and found to develop in different synoptic-scale situations. Warm barrier winds developed when there was a blocking high pressure over the Nordic seas, while cold barrier winds owed their presence to a train of cyclones channeling through the region.