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Editor's Highlight
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GEOPHYSICAL RESEARCH LETTERS,
VOL. 32,
L20708,
doi:10.1029/2005GL024233,
2005
A signature of persistent natural thermohaline circulation cycles in observed climate
Jeff R. Knight
Hadley Centre for Climate Prediction and Research, Met Office, Exeter, Devon, UK
Robert J. Allan
Hadley Centre for Climate Prediction and Research, Met Office, Exeter, Devon, UK
Chris K. Folland
Hadley Centre for Climate Prediction and Research, Met Office, Exeter, Devon, UK
Michael Vellinga
Hadley Centre for Climate Prediction and Research, Met Office, Exeter, Devon, UK
Michael E. Mann
Department of Meteorology and Earth and Environmental Systems Institute (ESSI), Pennsylvania State University, University
Park, Pennsylvania, USA
Abstract
Analyses of global climate from measurements dating back to the nineteenth century show an ‘Atlantic Multidecadal Oscillation’
(AMO) as a leading large-scale pattern of multidecadal variability in surface temperature. Yet it is not possible to determine
whether these fluctuations are genuinely oscillatory from the relatively short observational record alone. Using a 1400 year
climate model calculation, we are able to simulate the observed pattern and amplitude of the AMO. The results imply the AMO
is a genuine quasi-periodic cycle of internal climate variability persisting for many centuries, and is related to variability
in the oceanic thermohaline circulation (THC). This relationship suggests we can attempt to reconstruct past THC changes,
and we infer an increase in THC strength over the last 25 years. Potential predictability associated with the mode implies
natural THC and AMO decreases over the next few decades independent of anthropogenic climate change.
Received 1
August
2005;
accepted 22
August
2005;
published 25
October
2005.
Index Terms: 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 1626 Global Change: Global climate models (3337, 4928); 3339 Atmospheric Processes: Ocean/atmosphere interactions (0312, 4504); 4513 Oceanography: Physical: Decadal ocean variability (1616, 1635, 3305, 4215); 9325 Geographic Location: Atlantic Ocean.
Read Full Article (file size: 856158 bytes) Cited by
Citation: Knight, J. R., R. J. Allan, C. K. Folland, M. Vellinga, and M. E. Mann
(2005),
A signature of persistent natural thermohaline circulation cycles in observed climate,
Geophys. Res. Lett.,
32,
L20708,
doi:10.1029/2005GL024233.
Published in 2005 by the American Geophysical Union.
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