Figure 3.33. Atlantic Multi-decadal Oscillation index from 1850 to 2005 represented by annual anomalies of SST in the extratropical North Atlantic (30–65°N; top), and in a more muted fashion in the tropical Atlantic (10°N –20°N) SST anomalies (bottom). Both series come from HadSST2 (Rayner et al., 2006) and are relative to the 1961 to 1990 mean (°C). The smooth blue curves show decadal variations (see Appendix 3.A).