Winter by Pieter Breugel the Elder 1565

NAO Background


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NAO Climate Impacts

The Earth

Other Sites & References



AGU NAO Chapman Conference


Lamont Climate Group





The North Atlantic Oscillation (NAO) is one of the large-scale modes of variability in our climate system. As its name indicates, the NAO is centered on the North Atlantic Ocean basin. Here the atmospheric circulation normally displays a strong meridional (north-south) pressure contrast, with low pressure in the northern edge of the basin, centered close to Iceland, and high pressure in the subtropics, centered near the Azores. This pressure contrast drives the mean surface winds and the wintertime midlatitude storms from west to east across the North Atlantic, bringing warm moist air to the European continent. Meteorologists have long noticed that the monthly and seasonal (particularly wintertime) averaged sea level pressure in stations in Iceland and the Azores, display an out-of-phase relationship with one another. More precisely, there is a tendency for sea level pressure to be lower than normal in the Icelandic low pressure center when it is higher than normal near the Azores and vice versa. This fluctuation is referred to as the NAO. It is related to noticeable changes in monthly and seasonal averaged wind speed and direction over the ocean, and concomitant changes in the paths of wintertime storms and their effect over the ocean and Europe. The NAO is the dominant mode of atmospheric variability in the North Atlantic sector throughout the year, but it is most pronounced during the winter season. A group of scientists at the Lamont Doherty Earth Observatory are part of a large international effort to investigate the cause of the NAO and its effect on the regional and global climate.

A note to the visitors of this site: This WWW site is part of a group effort in progress to assemble relevant information on the NAO. We appreciate any input that may alert us to omissions and errors, or helps us in other ways to make this a useful source of information.

NAO-Chapman Conference Fall 2000 awarded!

A White Paper on the NAO describes our current understanding of the North Atlantic Oscillation as well as salient research questions.

LOAM-NAO gif movie (2.5 MB) LOAM-NAO gif movie (5MB) LOAM-NAO mpeg movie (0.3 MB)

This page is maintained by Martin Visbeck and Heidi Cullen