Air-sea interaction associated with barrier winds off SE Greenland: Observations and Modelling

The air-sea interaction associated with barrier winds of southeast Greenland will be presented, based on aircraft observations, NWP modelling and a new climatology. The climatology is 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) and Denmark Strait South (DSS). Events stronger than 20 m/s 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. These fluxes are consistent with those observed from aircraft and ship. 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 and lead to quite different associated total heat flux patterns.