Evolution of tidal amplitudes in the eastern Pacific Ocean

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 K-1 and M-2 amplitudes (vertical bar K-1 vertical bar and vertical bar M-2 vertical bar) are increasing, except for vertical bar M-2 vertical bar in the Gulf of Panama. North of 18 degrees N, vertical bar K-1 vertical bar and vertical bar M-2 vertical bar 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 vertical bar K-1 vertical bar and vertical bar M-2 vertical bar excludes mechanisms with strong frequency dependence. Increasing tidal amplitudes may impact ocean mixing, nutrient supply, primary production, fisheries, and coastal erosion. Citation: Jay, D. A. (2009), Evolution of tidal amplitudes in the eastern Pacific Ocean, Geophys. Res. Lett., 36, L04603, doi: 10.1029/2008GL036185.