North atlantic oscillation dynamics recorded in greenland ice cores
Carefully selected ice core data from Greenland can be used to reconstruct an annual proxy North Atlantic oscillation (NAO) index. This index for the past 350 years indicates that the NAO is an intermittent climate oscillation with temporally active (coherent) and passive (incoherent) phases. No indication for a single, persistent, multiannual NAO frequency is found. In active phases, most of the energy is located in the frequency band with periods less than about 15 years. In addition, variability on time scales of 80 to 90 years has been observed since the mid-19th century.
C. Appenzeller and T. F. Stocker, Climate and Environmental Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. M. Anklin, Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA.
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Appenzeller
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Stocker
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Anklin