Decadal Climate Variability associated with the Meridional Overturning Circulation and the North Atlantic Oscillation in a new Climate Model (CHIME)

• Main Author: Persechino, Aurelie
• Format: Conference Object
• Language: English
• Published: 2009
• Subjects: Marine Sciences; Meteorology and Climatology; North Atlantic; North Atlantic oscillation
• Online Access: http://cedadocs.ceda.ac.uk/348/; http://cedadocs.ceda.ac.uk/348/2/Poster_Persechino.pdf

Using statistical analysis, the study investigates the decadal variability in the Atlantic Meridional Overturning Circulation (AMOC) and the North Atlantic Oscillation (NAO) in a new-coupled climate model CHIME developed at the National Oceanography Centre, Southampton. Because of the well-known contribution of both the AMOC and NAO to the mild climate of Atlantic European region, understanding the mechanism leading to their strong variability is pre-requisite for developing decadal predictions. However, although it has been shown that the multidecadal AMOC fluctuations are associated with a spatial pattern of surface heat flux variations that bear a strong resemblance to the NAO, no conclusive evidence has yet been found that the AMOC variability is part of a dynamically coupled atmosphere-ocean mode. Therefore in this study, the mechanisms responsible for decadal variability and links between the AMOC and NAO are investigated using CHIME. This model is as similar as possible to HadCM3 with the important exception that the ocean component has been replaced by the Hybrid-coordinate model HYCOM. The dependence of simulated AMOC and NAO variability on ocean model type is thus addressed for the first time. Overall CHIME shows strong decadal variability in both the AMOC and the NAO, which can be of considerable interested from the perspective of decadal climate predictability.