5. Summary and discussions

#### 5.1 Summary of results

We have presented the salient features of several past studies, covering nearly all the global ocean, in efforts to understand the nature of tidal variability associated with mean sea level variability. Here, we will present a quick summary of the results, and then discuss some similarities of all results.

In the Pacific Ocean, out of 152 tide gauges considered, M2 TACs are significant at 89 gauge, and K1 TACs are significant at 76 gauges. For the combined tidal variability of these four tides, 54 stations (35%) are significantly correlated to variations in sea-level, with <sup>δ</sup>-HATs <sup>&</sup>gt;50 mm m<sup>1</sup> (i.e., <sup>&</sup>gt;5% of the sea level perturbation). In the Atlantic Ocean, 104 gauges have significant TACs, and for K1, 62 locations exhibit TACs that are significant. For the combination of the eight largest tides, there is a near even mix in the Atlantic of positive (40) and negative (47) δ-HATs. Finally, in Hong Kong, mixed results were seen for individual TACs, but δ-HATs were only important at a few semi-enclosed harbor locations, namely Quarry Bay (Victoria Harbor), and Tai Po Kau, where the largest positive feedbacks worldwide were seen.
