(Abbrev. NAO) - the NAO is a large-scale fluctuation in atmospheric pressure between the subtropical high pressure system located near the Azores in the Atlantic Ocean and the sub-polar low pressure system near Iceland and is quantified in the NAO Index. The surface pressure drives surface winds and wintertime storms from west to east across the North Atlantic affecting climate from New England to western Europe as far eastward as central Siberia and eastern Mediterranean and southward to West Africa.
A teleconnection pattern characterized by a north-south dipole of geopotential height and sea level pressure anomalies over the North Atlantic Ocean (2).
The North Atlantic oscillation (NAO) is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores high. It controls the strength and direction of westerly winds and storm tracks across the North Atlantic. It is related to and highly correlated with the Arctic oscillation.