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Variable tidal amplitude in Hawaiʻi and the connection to Pacific decadal climate variability
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  • Adam Thomas Devlin,
  • Philip Robert Thompson,
  • David A Jay,
  • Edward D Zaron
Adam Thomas Devlin
University of Hawaiʻi at Mānoa

Corresponding Author:[email protected]

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Philip Robert Thompson
University of Hawaii at Manoa
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David A Jay
Portland State University
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Edward D Zaron
Oregon State University
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Abstract

Analysis of multi-decadal tide records, satellite altimetry, and high-resolution oceanic reanalysis around the Hawaiian Ridge identifies correlations between offshore and onshore mean sea level (MSL), M2 tidal amplitudes, and ocean stratification; these are linked to Pacific decadal climate variability. Empirical orthogonal function analyses reveal strongly correlated quasi-decadal variability in onshore and offshore tides and MSL, and all three factors are highly correlated with regional density stratification. This decadal variability is highly correlated with multiple Pacific climate indices, suggesting that this climate variability influences internal tides via coupled ocean-atmosphere mechanisms. The surface expression of variations in the M2 internal tide yield correlated variability between MSL and M2 offshore and onshore. The M2 signals at all tide gauges have stronger relationships to MSL in the altimetry era (1992-2023) than their respective full records, and both factors show stronger connections to climate variations in recent years. The M2 signal at Hilo is most clearly connected to climate variability over its full record, stronger even than the MSL-climate connections at all tide gauges. The amplitudes of the climate-induced tidal variations are on are on the order of 10% on top of MSL variability and long-term steric sea level rise. This amplification may exacerbate the frequency of high-tide flooding (also known as “sunny-day flooding”) in harbors and other low-lying areas of Hawai’i, highlighting the need for dynamic coastal management strategies that integrate astronomical, non-astronomical, and climatic factors, in sea level projections.
10 Jul 2024Submitted to ESS Open Archive
11 Jul 2024Published in ESS Open Archive