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Geophysical Research Letters

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Sea level -- Climatic factors -- Pacific Ocean, Tides -- Pacific Ocean -- Environmental impact analysis


Global sea level (GSL) rise is well documented. However, changes in high waters, including the tidal contribution, are sometimes more relevant than GSL rise. Analysis of 34 long tidal records from the Eastern Pacific Ocean shows that K1 and M2 amplitudes (∣K₁∣ and ∣M₂∣) are increasing, except for ∣M2∣ in the Gulf of Panama. North of 18°N, ∣K1∣ and ∣M2∣ are both growing at 2.2% century⁻¹. The mean increase in total tidal amplitude (0.59 mmyr⁻¹) is less than the present GSL rise (1.7 mmyr⁻¹). However, mean sea level is nearly constant in the NE Pacific, so tidal evolution plays a major regional role in changes in high water levels. The spatial pattern of tidal evolution suggests the influence of large-scale processes, and the similarity in spatial patterns for ∣K₁∣ and ∣M₂∣ excludes mechanisms with strong frequency dependence. Increasing tidal amplitudes may impact ocean mixing, nutrient supply, primary production, fisheries, and coastal erosion.


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