Observational and Modeling Evidence for a Multi‐Decadal Shift in Longshore Sediment Transport Patterns From a Changing Wave Climate Along the Atlantic Coast of the Southeastern US

Abstract Longshore sediment transport (LST) is influenced by storms, background wave climate, and shoreline orientation. While shifts in Pacific wave climate have been shown to reverse the LST direction, studies investigating these links in the Atlantic are few despite reported changes in storms and wave climate. Here, a novel technique is applied along 50 km of the Southeastern Atlantic coast of North America where satellite‐derived shoreline orientations and wave hindcasts are coupled to model changes in LST from 1984 to 2022. This method assesses how changes in wave climate and storminess influence coherent changes in LST patterns in the Southeast Atlantic and examines the relative influence of storm and non‐storm wave conditions on LST. Our analyses reveal that storms drive sporadic shifts in LST indicative of stochastic processes, while non‐storm intervals are characterized by coherent shifts to more northern‐directed LST from an increasingly southern wave climate and increased wave energy. These results indicate that non‐storm waves drive an increasing portion of LST relative to storms over the past ∼40 years and are becoming a dominant driver of shoreline change in the Southeast Atlantic. Furthermore, this work demonstrates that the shift to more southerly non‐storm waves is statistically significantly correlated with an equatorial migration of mid‐Atlantic basin sea level pressure (SLP) highs. This work is among the first to show that changing wave conditions and LST dynamics in the Atlantic are likely driven by latitudinal shifts in wind‐producing SLP gradients, which may significantly alter sediment transport regimes along the southeastern US Atlantic coast.