Regional climate impacts of the Northern Hemisphere annular mode

David W. J. Thompson, John M. Wallace

Research output: Contribution to journalArticlepeer-review

762 Citations (Scopus)


The Northern Hemisphere annular mode (NAM) (also known as the North Atlantic Oscillation) is shown to exert a strong influence on wintertime climate, not only over the Euro-Atlantic half of the hemisphere as documented in previous studies, but over the Pacific half as well. It affects not only the mean conditions, but also the day-to-day variability, modulating the intensity of mid-latitude storms and the frequency of occurrence of high-latitude blocking and cold air outbreaks throughout the hemisphere. The recent trend in the NAM toward its high-index polarity with stronger subpolar westerlies has tended to reduce the severity of winter weather over most middle- and high-latitude Northern Hemisphere continental regions.
Original languageEnglish
Pages (from-to)85-89
Number of pages5
Issue number5527
Publication statusPublished - 6 Jul 2001

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