Figure 5. (a) and (b) present the leading EOF (φ1) of the gridded, tide gauge obtained, sea-level anomaly (circular markers). (c) and (d) present, for the Pacific and Atlantic respectively, the associated principal components α1’s (solid blue lines), together with indices of extension meridional location: this study and Qiu et al. (2016) T/S-based and wind-based KEIs (on (c), thick light blue line, orange solid line and dot-dashed red line respectively); and this study and Joyce et al. (2000) GSNWs (on (d), thick light blue line and dot-dashed red line, respectively) . All quantities on (c) and (d) are normalized. Colour shadings on (a) and (b) are, for each basin, the sea surface velocity magnitude composites difference based on the principal component α1 (period of α1 >+2/3 minus period of α1 <−2/3). The arbitrary threshold of ±2/3 was used, but taking any number between zero and one leads to akin patterns. The inset on (a) present the regression coefficient obtained when the principal component is regressed on the original tide gauges, with a zoom in on the Kii peninsula.
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