Characteristics of storms driving wave-induced seafloor mobility on the U.S. East Coast continental shelf

Abstract

a b s t r a c tThis study investigates the relationship between spatial and temporal patterns of wave-driven sediment mobility events on the U.S. East Coast continental shelf and the characteristics of the storms responsible for them. Mobility events, defined as seafloor wave stress exceedance of the critical stress of 0.35 mm diameter sand (0.2160 Pa) for 12 or more hours, were identified from surface wave observations at National Data Buoy Center buoys in the Middle Atlantic Bight (MAB) and South Atlantic Bight (SAB) over the period of 1997-2007. In water depths ranging from 36-48 m, there were 4-9 mobility events/year of 1-2 days duration. Integrated wave stress during events (IWAVES) was used as a combined metric of wave-driven mobility intensity and duration. In the MAB, over 67% of IWAVES was caused by extratropical storms, while in the SAB, greater than 66% of IWAVES was caused by tropical storms. On average, mobility events were caused by waves generated by storms located 800þ km away. Far-field hurricanes generated swell 2-4 days before the waves caused mobility on the shelf. Throughout most of the SAB, mobility events were driven by storms to the south, east, and west. In the MAB and near Cape Hatteras, winds from more northerly storms and low-pressure extratropical systems in the mid-western U.S. also drove mobility events. Waves generated by storms off the SAB generated mobility events along the entire U.S. East Coast shelf north to Cape Cod, while Cape Hatteras shielded the SAB area from swell originating to the north offshore of the MAB.Published by Elsevier Ltd.

Typhoon Soudelor (2015) Induced Offshore Movement of Sand Dunes and Geomorphological Change: Fujian Coast, China

“…In an extreme dynamic typhoon process, the strong cyclonic wind stress overturns the original flow structure and forms short-term typhoon-induced currents. Meanwhile, the typhoon-induced storm waves by strong cyclonic winds can directly stir the submarine sediments, inducing re-suspension and re-transport of unconsolidated submarine sediments [8,12,13]. This strong dynamic process changes the water body (dynamic) structure and affects the suspension, transport, and distribution of sediments, thus resulting in changes in the marine sedimentation process and submarine geomorphology (i.e., movement of sand dunes and geomorphological changes).…”

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Hydrodynamics and Sediment Mobility Processes Over a Degraded Senile Coral Reef

“…A seabed hydrodynamic roughness length scale ( k N ) corresponding to d 50 /30 was used to derive the skin friction (force acting on the sediment). When the ratio between the calculated wave‐current bottom stress and critical shear stress exceeded one ( τ wc / τ crit > 1), the sediment at that location was estimated to be mobilized (Dalyander & Butman, ; Soulsby, ).…”