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Pohlmann, H.
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Pohlmann, H.
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- PublicationRestrictedInterannual to Decadal Climate Predictability in the North Atlantic: A Multi-Model-Ensemble Study(2006)
; ; ; ; ; ; ; ; ; ; ; ; ;Collins, M.; Hadley Centre, Met Office, Exeter, United Kingdom ;Botzet, M.; Max-Planck-Institut für Meteorologie, Hamburg, Germany ;Carril, A. F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Drange, H.; Nansen Environmental and Remote Sensing Center, and Bjerknes Centre for Climate Research, Bergen, Norway ;Jouzeau, A.; CERFACS, Toulouse, France ;Latif, M.; Max-Planck-Institut für Meterologie, Hamburg, and Leibniz-Institut für Meereswissenschaften, Kiel, Germany ;Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Otteraa, O. H.; Nansen Environmental and Remote Sensing Center, and Bjerknes Centre for Climate Research, Bergen, Norway ;Pohlmann, H.; Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada ;Sorteberg, A.; Bjerknes Centre for Climate Research, Bergen, Norway ;Sutton, R.; Centre for Global Atmospheric Modelling, Reading, United Kingdom ;Terray, L.; CERFACS, Toulouse, France; ; ;; ; ; ; ; ; ; ; Ensemble experiments are performed with five coupled atmosphere–ocean models to investigate the potential for initial-value climate forecasts on interannual to decadal time scales. Experiments are started from similar model-generated initial states, and common diagnostics of predictability are used. We find that variations in the ocean meridional overturning circulation (MOC) are potentially predictable on interannual to decadal time scales, a more consistent picture of the surface temperature impact of decadal variations in the MOC is now apparent, and variations of surface air temperatures in the North Atlantic Ocean are also potentially predictable on interannual to decadal time scales, albeit with potential skill levels that are less than those seen for MOC variations. This intercomparison represents a step forward in assessing the robustness of model estimates of potential skill and is a prerequisite for the development of any operational forecasting system.313 62 - PublicationRestrictedPredictability of the mid-latitude Atlantic meridional overturning circulation in a multi-model system(2013)
; ; ; ; ; ; ; ; ;Pohlmann, H.; Max-Planck-Institut fu ̈r Meteorologie, ;Smith, D. M.; Met Office Hadley Centre ;Balmaseda, M. A.; ECMWF ;Keenlyside, N. S.; Geophysical Institute and Bjerknes Centre, University of Bergen ;Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Matei, D.; Max-Planck-Institut fu ̈r Meteorologie, ;Muller, W. A.; Max-Planck-Institut fu ̈r Meteorologie, ;Rogel, P.; CERFACS; ; ; ; ; ; ; Assessing the skill of the Atlantic meridional overturning circulation (AMOC) in decadal hindcasts (i.e. retrospective predictions) is hampered by a lack of obser- vations for verification. Models are therefore needed to reconstruct the historical AMOC variability. Here we show that ten recent oceanic syntheses provide a common signal of AMOC variability at 45°N, with an increase from the 1960s to the mid-1990s and a decrease thereafter although they disagree on the exact magnitude. This signal corre- lates with observed key processes such as the North Atlantic Oscillation, sub-polar gyre strength, Atlantic sea surface temperature dipole, and Labrador Sea convection that are thought to be related to the AMOC. Furthermore, we find potential predictability of the mid-latitude AMOC for the first 3–6 year means when we validate decadal hindcasts for the past 50 years against the multi-model signal. However, this predictability is not found in models driven only by external radiative changes, demonstrating the need for initialization of decadal climate predictions.492 103