Arctic oscillation
Positive and negative phases of the Arctic Oscillation The Arctic oscillation ( AO ) or Northern Annular Mode / Northern Hemisphere Annular Mode ( NAM ) is a weather phenomenon at the Arctic and Antarctic poles north (or south) of 20 degrees latitude. The index varies over time with no particular periodicity, and is characterized by non-seasonal sea-level pressure anomalies of one sign in the Arctic, balanced by anomalies of opposite sign centered at about 37–45N. [1] The North Atlantic oscillation (NAO) is a close relative of the AO. There is debate over whether one or the other is more fundamentally representative of the atmosphere's dynamics. The NAO may be identified in a more physically meaningful way, which may carry more impact on measurable effects of changes in the atmosphere. [2] Contents 1 Description 2 Periodicity 3 Impacts 4 Events of 2010 5 See also 6 References 7 External links Description The AO appears as a ringlik...