29-04-2010: Arctic sea-ice melt in 2007

During summer 2007 the Arctic sea-ice shrank to the lowest extent ever observed. Unusual atmospheric conditions prevailed in the Arctic that summer, with a persistent high pressure over the Beaufort Sea north of Canada and a low pressure over the northeastern Siberia. These conditions caused atmospheric flow of warm and humid air into the region that suffered severe melt. This led to an increase of the downward longwave radiation at the surface. In the region that experienced unusual ice melt, the enhancement of the surface energy fluxes provided enough extra energy to melt roughly one meter of ice during the melting season. We argue that the positive anomalies of downward longwave radiation and turbulent fluxes at the surface played a key role in initiating the 2007 extreme ice melt.