Treffer: The Influence of Wave Events on Open Water Suspended Sediment Fluxes on the Alaskan Beaufort Sea Shelf: A Numerical Modeling Study.

Suspended sediment fluxes on continental shelves impact geomorphology, habitats, and biogeochemistry. In the coastal Arctic, the rate at which sediment is transported to locations where it can be sequestered also impacts the fate of carbon from thawing permafrost. This study used a numerical model to analyze the role of wave events on open water suspended sediment fluxes over hourly to monthly timescales. A coupled hydrodynamic—sediment transport model, the Regional Ocean Modeling System—Community Sediment Transport Modeling System, was implemented within the Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport (COAWST) Modeling System for the 2020 open water season on the Alaskan Beaufort Sea shelf. Results showed that wave‐ and current‐induced bed shear stresses were frequently capable of resuspending sediment. Waves dominated bed shear stresses in depths shallower than 10 m and currents dominated in depths deeper than 20 m. Suspended sediment flux directions oscillated with the currents, which were eastward on average. However, since large waves tended to occur during westward currents, time‐averaged suspended sediment fluxes on the inner shelf were westward. Sensitivity tests were performed where significant wave heights were (a) set to zero and (b) doubled, which showed that waves increased the fraction of time that sediment could be resuspended by up to 50% and increased westward suspended sediment fluxes on the inner shelf. Overall, the results improve our understanding of how waves impact sediment fluxes on the Beaufort Sea shelf during the open water season and suggest that terrestrially derived sediment may be transported westward along the inner shelf. Plain Language Summary: The transport of sediment (mud and sand) in the coastal ocean impacts the evolution of coastlines, health of habitats, and associated carbon and nutrients that are important for biological and chemical processes. We used a computer model to better understand which processes drive the movement of sediment on the timescales of hours to months during the summer when there is little sea ice in the coastal Arctic Ocean. We focused on the Alaskan Beaufort Sea nearshore region during July–October 2020. Our findings indicated that strong waves led to more sediment in the water column for regions shallower than 10 m whereas currents led to more sediment in the water column for regions deeper than 20 m. The direction of sediment transport in the water column oscillated with the currents, which were eastward on average. We ran the model with different wave conditions and found that waves were important and increased the westward movement of sediment in nearshore regions. We expect strong wave events may become more important for future sediment transport, which would cause more westward flows of sediment along the shelf. Overall, our results improve our understanding of summer sediment dynamics on the Alaskan Beaufort Sea shelf. Key Points: A hydrodynamic—sediment transport numerical model was implemented for the Alaskan Beaufort Sea shelf for a nearly ice‐free periodSediment fluxes on the inner shelf were driven by wave‐induced resuspension that most frequently co‐occurred with westward currentsIncreases in waves may enhance westward suspended sediment fluxes, despite time‐averaged currents being eastward [ABSTRACT FROM AUTHOR]

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