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

Abstract

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 ((Formula presented.) 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 ((Formula presented.) 1960–1990) and incoherence ((Formula presented.) 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.