North American East Coast Sea Level Exhibits High Power and Spatiotemporal Complexity on Decadal Timescales

Tide gauges provide a rich, long-term, record of the amplitude and spatiotemporal structure of interannual to multidecadal coastal sea-level variability, including that related to North American east coast sea level hotspots. Here, using wavelet analyses, we find evidence for multidecadal epochs of enhanced decadal (10-15 year period) sea-level variability at almost all long (>70 years) east coast tide gauge records. Within this frequency band, large-scale spatial covariance is time-dependent; notably, coastal sectors north and south of Cape Hatteras exhibit multidecadal epochs of coherence (similar to 1960-1990) and incoherence (similar to 1990-present). Results suggest that previous interpretations of along coast covariance, and its underlying physical drivers, are clouded by time-dependence and frequency-dependence. Although further work is required to clarify the mechanisms driving sea-level variability in this frequency band, we highlight potential associations with the North Atlantic sea surface temperature tripole and Atlantic Multidecadal Variability.

Automated summary

Using wavelet analyses, the study finds evidence of enhanced multidecadal sea-level variability in long east coast tide gauge records. Spatial covariance within this frequency band is time-dependent, with coastal sectors north and south of Cape Hatteras exhibiting different epochs of coherence. Results suggest that previous interpretations of along coast covariance are affected by time-dependence and frequency-dependence, potentially associated with North Atlantic sea surface temperature tripole and Atlantic Multidecadal Variability.