4.1 Data inventory and sources

We now present some of the best results from past studies. Pacific Ocean locations were analyzed in Devlin et al. [9] for individual TACs, whereas Devlin et al. [8] analyzed the combined tidal variability of the δ-HATs, 152 total locations were analyzed in both Pacific studies. Locations are shown in Figures 3 and 4 (Eastern Pacific and Western Pacific, respectively) with major water basins labeled. The Atlantic Ocean was analyzed in Devlin et al. [10], which calculated both TACs

and δ-HATs, considering a total of 170 locations. Atlantic locations are displayed in Figure 5 and major basins are labeled. Most of the hourly tide gauge records in the Pacific and Atlantic are obtained from the University of Hawaii's Sea Level Center

Figure 3.

Red dots indicate gauge locations in the Eastern Pacific [9]. Color bar indicates water depth, in meters. Areas with a depth less than 100 m are shaded gray, and land is black.

#### Figure 4.

Red dots indicate gauge locations in the Western Pacific [9]. Color bar indicates water depth, in meters. Areas with a depth less than 100 m are shaded gray, and land is in black.

(UHSLC), with additional data from the following agencies: The Japanese Oceanographic Data Center (JODC); Canada's Fisheries and Ocean office (FOC); Australia's National Tidal Center (AuNTC), and the remainder from the Global Extreme Sea Level Analysis dataset, 2nd edition (GESLA [61]; www.gesla.org), an archiving project that has gathered high-frequency water level data into a single standardized data format from multiple worldwide monitoring agencies. Finally, a close regional study of the tidal variability (individual and combined) of the Hong Kong tide gauge network (12 gauges) was performed in Devlin et al. [11]; this data was obtained from the Hong Kong Observatory (HKO) and the Hong Kong Marine Department (HKMD); locations are shown in Figure 6. For the Pacific and Hong Kong studies, the four largest tidal constituents (M2, S2, K1, and O1) and their combinations (δ-HAT) were considered. The Atlantic study also considered four more tides (N2, K2, P1, and Q1), and the combined δ-HAT considered here involved all eight components. However, for the sake of brevity in this chapter, only the largest semidiurnal (M2) and diurnal (K1) tide results will be discussed, along with δ-HAT determinations.

In all Pacific plots, the magnitude of the TACs or δ-HATs are indicated by the color intensity of the dots according to the scale shown in the legend; positive TACs are in shades of red, negative TACs are in shades of blue. For a gauge with an insignificant TAC (signal-to-noise ratio less than 2.0), the dots are white. In the Atlantic and Hong Kong results, red markers indicate positive TACs and blue markers indicate negative TACs, with magnitudes proportional to marker size, as shown in the legend, and insignificant results are shown as black dots. These values provide a measure of the tidal response, normalized to a 1 m MSL rise. In the TAC plots, the green and yellow background fields show the mean value of tidal

Figure 5. Gauge locations analyzed in the Atlantic Ocean. The colored background shows water depth, in units of meters [10].

#### Figure 6.

Tide gauge locations in Hong Kong used in this study [11]. Green markers indicate active gauges provided by the Hong Kong Observatory (HKO), light blue markers indicate gauges provided by the Hong Kong marine department (HKMD), and red markers indicate historical gauges (once maintained by HKO) that are no longer operational.

amplitudes over the satellite altimetry record (1993–2014), using a tidal solution from the TPXO7.2 tide model [62, 63].

### 4.2 Pacific results
