Arctic oscillation

The Arctic Oscillation (AO ) or Northern Hemispheric Annular Mode (NAM ), is an expression of the pressure contrast between the Arctic and mid-latitudes in the northern hemisphere. It is caused by the large temperature differences between the extremely cold polar regions and the temperate mid-latitudes. The thereby developing winds are deflected due to the Coriolis force to the east.

Like all currents can also be the AO divided into two phases: In the positive phase drift in the winter strong westerly winds, the warm air from the Atlantic to northern Europe and Siberia, and the polar regions. This has a direct negative impact on the local ice thickness. In the negative phase, cold polar air to penetrate further south. The result is a severe winter in Europe.