Arctic Oscillation


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Arctic Oscillation

[¦ärd·ik ‚äs·ə′lā·shən]
(meteorology)
Atmospheric pressure fluctuations (positive and negative phases) between the polar and middle latitudes (above 45° North) that strengthen and weaken the winds circulating counterclockwise from the surface to the lower stratosphere around the Arctic and, as a result, modulate the severity of the winter weather over most Northern Hemisphere middle and high latitudes. Also known as the Northern Hemisphere annular mode.
References in periodicals archive ?
Arctic Oscillation (also named Northern Annular Mode) is a dominant pattern of non-seasonal SLP variations north of 20[degrees]N latitude and is characterized by pressure anomalies of one sign in the Arctic with the opposite anomalies centred on sub-tropical latitudes about 37-45[degrees]N.
The Arctic Oscillation signature in the wintertime geopotential height and temperature fields.
The Arctic oscillation causes the typical flip-flop from cold to warm weather every few years.
Atmospheric temperatures in northern Europe and Asia dance in step with this Arctic oscillation.
For most of the century, the Arctic oscillation shifted randomly from month to month and year to year, with no distinct preference for either extreme.
The largest wind speed anomalies of the quarter - both positive and negative - were found in Europe and North Africa, a pattern that can be explained in part by the Arctic Oscillation (AO).
Diminishing Arctic sea ice can cause changes in atmospheric circulation that lead to a circulation pattern that is different than the "negative phase" of the Arctic Oscillation.
However, the direction of a meteorological index known as the Arctic Oscillation (AO) is likely to be the key to good conditions for the remainder of the season.
They believe the increased snow cover has an intricate effect on the Arctic Oscillation - an atmospheric pressure pattern in the mid- to high-latitudes - causing it to remain in the "negative phase".

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