North Atlantic Oscillation–related climate variability in a regional atmospheric model

Abstract

Climate variability over the Greenland ice sheet associated with the North Atlantic Oscillation (NAO) is simulated with the Polar MM5 (PMM5) regional climate model (RCM). Two five‐member monthly ensembles, each representative of high or low NAO extremes, are made, with data from the European Centre for Medium‐Range Weather Forecasts 40‐year reanalysis (ERA‐40) used to provide the forcing for the RCM runs. Ensemble differences between the high and low NAO cases are discussed, and model output is compared to ERA‐40 and to observations from automatic weather stations over Greenland. PMM5 is shown to reproduce several well‐known features of NAO‐related climate variability in the Greenland region, including colder near‐surface air temperatures, lower sea level pressure, stronger westerly winds south of Greenland, and reduced precipitation over western Greenland and the Labrador Sea during high NAO months.