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 pole north of 55 degrees latitude.

Aug 30, 2009 · Winter surface pressure across the Northern Hemisphere compared to the 1981-2010 average when the Arctic Oscillation (AO) was strongly negative (top, 2009-10) and when it was strongly positive (bottom, 1988-89). The negative AO favors a warm Arctic and cool conditions across the U.S. and Europe.

The Arctic Oscillation (AO) is a large scale mode of climate variability, also referred to as the Northern Hemisphere annular mode. The AO is a climate pattern characterized by winds circulating counterclockwise around the Arctic at around 55°N latitude.

Sep 1, 2021 · Conversely, when pressure north of the Arctic Circle is higher than normal, the Arctic Oscillation is deemed to be negative. A negative AO leads to a weaker, buckled polar jet (right image Figure 2). The more negative the AO climate index, …

Oct 26, 2020 · When the Arctic Oscillation is in its negative mode, the winds and ice tend to flow in a clockwise direction, generally keeping more of the older, thicker ice in the middle of the Arctic. In the positive phase, that old ice tends to get pushed out of the Arctic along the Greenland coast.

The Arctic Oscillation (AO) is a phenomenon that describes how surface air pressure patterns relate to each other in the mid- to high-latitudes. This relationship influences the jet stream, which is a band of strong winds in the upper atmosphere that generally separates warm and cold air.

The Arctic Oscillation (AO), shown below, is an important Arctic climate index with positive and negative phases, which represents the state of atmospheric circulation over the Arctic. The positive phase (red) brings lower-than-normal pressure over the polar region, steering ocean storms northward, bringing wetter weather to Scotland and ...

Feb 10, 2025 · The Arctic Oscillation (AO) is currently negative and is predicted to remain negative to neutral the next two weeks as pressure/geopotential height anomalies across the Arctic are currently mostly mixed and are predicted to …

The Arctic Oscillation refers to opposing atmospheric pressure patterns in northern middle and high latitudes. The oscillation exhibits a “negative phase” with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a “positive phase” in which the pattern is reversed.

Mar 2, 2011 · When the AO index is positive and the vortex intense, the winds tighten like a noose around the North Pole, locking cold air in place. A negative AO and weak vortex … allow intrusions of cold air to plunge southward into North America, Europe, and Asia. … the index has been mostly positive in wintertime since the late 1980s.