A dynamical systems framework, in many ways similar to that for El Nino/Southern Oscillation, is presented to unterstand the multidecadal varability in the North Atlantic. A so-called minimal primitive equation model is forst used to represent the multidecadal variability in the North Atlantic climate system. Within this minimal model, we identify a normal mode of multidecadas variability tha can destabilize the background climate state throught a so-called Hopf bifurcation. Next, it is argued that noise is setting the amplitude of the sea surface temperature variability associated with this normal mode. Finally, it will argued that the machanism found in the minimal model is responsible for the multidecadal variability in GCMs and in available observations.
02.02.2012
15:15 Uhr