Can extreme internal waves trigger turbidity currents and carbon transport in submarine canyons?

点击翻译按钮获取中文摘要

Scientific background:Submarine canyons play a key role in the transport of sediment and carbon from shelf seas to the deep ocean by funnelling sediment-laden turbidity currents and cold-salty density currents down the continental slope. These currents are sporadic and the processes that trigger them poorly understood, so their overall contribution to global sediment and carbon budgets remains uncertain. One proposed triggering mechanism involves large-amplitude internal (subsurface) waves, which are generated by ocean tides and focused into submarine canyons. Internal waves increase near-bed current speed and particularly energetic internal wave events may resuspend enough sediment to form turbidity currents. Project objectives:1) Investigate how internal waves resuspend sediment and carbon.2) Identify triggering thresholds.3) Determine down-canyon sediment and carbon transport.Research methodology:You will analyse long-duration hydrodynamic, sedimentological and biogeochemical data from Whittard Canyon, a large branching submarine canyon system that incises the Celtic Sea continental shelf. Using autonomous ocean glider and acoustic Doppler current profiler (ADCP) mooring data, you will first map the spatial and seasonal variability of internal waves within the canyon to identify where and when triggering events are most likely. Then, using data from sediment traps and biogeochemical sensors, you will investigate the mechanisms by which internal waves resuspend sediment and carbon, identify triggering thresholds, and quantify down-canyon sediment and carbon transport. Finally, you will compare your results from Whittard Canyon with other canyon systems worldwide.