Figure 2

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Figure 2. Atlantic sector of the first rotated EOF of non-ENSO global SST variability for 1870-2000 referred to as the "Atlantic multidecadal mode" (38, 39). (A) Spatial distribution of correlations between local monthly SST anomalies and the modal reconstruction over the indexed region (northern rectangle), the general area where the mode amplitude is the strongest. This distribution has a similar spatial structure to the actual rotated EOF and gives a measure of the local fractional variance (squared temporal correlation) accounted for at each grid point. Dashed lines give north and south boundaries of main development region (MDR) and box (10° to 14°N, 20° to 70°W) is region used to calculate data for Fig. 3. (B) Temporal reconstruction (annual means) of the mode-related variability averaged over the rectangular areain (A). Dashed curved lineis 5-year running mean. Although the signal is stronger in the North Atlantic, it is global in scope with positively correlated co-oscillations in parts of the North Pacific (55). For the multidecadal variations shown here, the coherence between the MDR and far North Atlantic is a robust feature. The SST fluctuations in the far North Atlantic could be used as a proxy for changes in the MDR.