4.2.1 Pacific M2 TACs

The M2 TACs do not reveal any coherent basin-wide patterns of variability, however, there are localized features of interest. In the Eastern Pacific (Figure 7), river-influenced gauges, such as San Francisco, California, Astoria, Oregon (labeled as "SF" and "AST" on the map) exhibit strong negative TACs. Strongly positive M2 TACs are observed at many Hawaiian and Alaskan gauges. Other locations show only weak or isolated correlations. At one gauge of note, Puerto Montt in far southern Chile (labeled as "PM" in Figure 7), there is an exceptionally large negative M2 TAC, greater than 500 mm m<sup>1</sup> . There are a higher number M2 TACs in the Western Pacific than in the Eastern Pacific, but again the relevant variability is local (Figure 8). M2 TACs are negative for the majority of Japan and Taiwan, some exceeding 100 mm m<sup>1</sup> . However, some large positive M2 TACs are at isolated locations, such as at Okada (labeled as "OKA" in Figure 8) and in Tokyo harbor ("TOK"). At Hong Kong ("HK"), one of the largest positive M2 TACs is found (discussed in further detail below). Most significant positive TACs are south of the equator, and most negative TACs are north of the equator. The correlations at nearly all gauges in Malaysia (40 to 150 mm m<sup>1</sup> ) and in the Philippines (80 to 145 mm m<sup>1</sup> ) are strongly negative. Finally, Honiara ("HON") in the Solomon Islands and Rabaul, Papua New Guinea ("RAB") have small mean M2 amplitudes (50 mm) but display large relative correlations.

#### Figure 7.

M2 TAC map in the Eastern Pacific [9], showing changes in amplitude (per m MSL rise). Map background shows mean tidal amplitudes (meters, green color scale) from the ocean tidal model of TPXO7.2 [62, 63]. Red and blue colored markers show positive and negative TACs, respectively. The magnitudes are indicated by color intensity, as shown by legend at the bottom, in units of mm of tidal change per meter of sea level rise (mm m<sup>1</sup> ). TACs are only plotted if the ratio of the 95% confidence limit of the trends has a signal-to-noise ratio of >2.0. Statistically insignificant values are indicated by white circles. Maps were generated using MATLAB version R2011a (www.mathworks.com).
