North Atlantic Oscillation

The North Atlantic Oscillation is a fluctuation in atmospheric pressure differences between the subtropical Atlantic and the region near Iceland. Its phases shift the strength and position of Atlantic westerly winds, influencing weather around the North Atlantic.

Azores High: A persistent subtropical high-pressure system over the North Atlantic near the Azores. Its pressure helps define the southern side of the oscillation.
NAO+: The North Atlantic Oscillation phase with an unusually strong pressure gradient between the subtropical Atlantic and Iceland. This phase typically strengthens westerlies and brings milder, wetter winters to northern Europe.
Sir Gilbert Walker: A British meteorologist who identified large-scale atmospheric pressure oscillations in the early twentieth century. His work established the statistical study of atmospheric oscillations.
Arctic Oscillation: A hemispheric atmospheric pattern describing pressure variations between the Arctic and midlatitudes. It resembles the NAO but spans a broader, more zonally symmetric region.
Icelandic Low: A semipermanent low-pressure region near Iceland and the Greenland Sea. Its pressure helps define the northern side of the oscillation.
European winter climate: The seasonal patterns of temperature, precipitation, and circulation across Europe during winter. NAO phases strongly shape winter weather contrasts between northern and southern Europe.
East Atlantic pattern: A recurring North Atlantic–European atmospheric circulation pattern distinct from the NAO. Its identification helped distinguish the NAO from neighboring circulation variability.
East Atlantic–West Russia pattern: A recurring circulation pattern linking pressure anomalies over the eastern Atlantic and western Russia. It can produce European climate anomalies that the NAO alone does not explain.
North Atlantic jet stream: A band of strong westerly winds in the upper troposphere over the North Atlantic. The oscillation shifts the jet's strength and latitude.
Greenland blocking: A persistent high-pressure circulation pattern over Greenland that disrupts the usual westerly flow. Blocking often accompanies negative NAO conditions and redirects Atlantic storms.

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