DECADAL TRENDS IN THE NORTH-ATLANTIC OSCILLATION - REGIONAL TEMPERATURES AND PRECIPITATION

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TitleDECADAL TRENDS IN THE NORTH-ATLANTIC OSCILLATION - REGIONAL TEMPERATURES AND PRECIPITATION
Publication TypeGeneral Resource
Year of Publication1995
AuthorsHurrell, J. W.
Science
Volume269
Pagination676-679
Type of ArticleJournal Article
ISSN0036-8075
Abstract

Greenland ice-core data have revealed large decadal climate variations over the North Atlantic that can be related to a major source of low-frequency variability, the North Atlantic Oscillation. Over the past decade, the Oscillation has remained in one extreme phase during the winters, contributing significantly to the recent wintertime warmth across Europe and to cold conditions in the northwest Atlantic. An evaluation of the atmospheric moisture budget reveals coherent large-scale changes since 1980 that are linked to recent dry conditions over southern Europe and the Mediterranean, whereas northern Europe and parts of Scandinavia have generally experienced wetter than normal conditions.

DOI10.1126/science.269.5224.676
Citation Key1264
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Comments

The Arctic Oscillation (AO), which for this discussion is equivalent to the North Atlantic Oscillation and the Northern Annular Mode, is the predominant mode of middle and high latitude variability in the northern hemisphere. This is true for the entire year, but the AO's influence is most visible in the winter and early spring. Prior to 1960 the the behavior of the AO is more or less random from one year to the next, which is consistent with climate models. After 1960 there is persistence of patterns from one year to the next, which suggests that something has changed. Models with increasing carbon dioxide better reproduce this persistence, suggesting a relation to greenhouse gas forcing. The AO is a difficult to predict atmospheric process, which is different from El Nino and La Nina. The El Nino - La Nina cycle is an atmospheric-oceanic oscillation, with some predictability. The massive reduction of Arctic sea ice and large changes in northern hemisphere snow cover are important changes that occurred after this paper was published and whose impacts need to be evaluated.