Causes of Interannual–Decadal Variability in the Meridional Overturning Circulation of the Midlatitude North Atlantic Ocean

• DOI: 10.1175/2008jcli2404.1
• Publication Date: 2008-06-20T15:35:45Z
• Authors: Arne Biastoch; Claus W. Böning; Julia Getzlaff; Jean-Marc Molines; Gurvan Madec
• Keywords: Forcing (mathematics); Hindcast; Middle latitudes; Tropical Atlantic

Abstract The causes and characteristics of interannual–decadal variability the meridional overturning circulation (MOC) in North Atlantic are investigated with a suite basin-scale ocean models [the Family Linked Model Experiments (FLAME)] global ocean–ice (ORCA), varying resolution from medium to eddy resolving (½°–1/12°), using various forcing configurations built on bulk formulations invoking atmospheric reanalysis products. Comparison model hindcasts indicates similar MOC time scales up decade; both architectures also simulate an upward trend strength between early 1970s mid-1990s. changes examined by perturbation experiments aimed selectively at response individual components. solutions emphasize inherently linear character midlatitude demonstrating that anomalies (non–eddy resolving) hindcast simulation can be understood as superposition decadal longer-term signals originating thermohaline variability, higher-frequency wind-driven variability. signal is linked subarctic deep-water formation, rapidly progressing tropical Atlantic. However, throughout subtropical Atlantic, this effectively masked stronger related wind and, especially north 30°–35°N, internally induced (eddy) fluctuations.