Collaborative Research: Dynamics of Cross-Shelf Plumes under Upwelling Wind Conditions

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The project will investigate the linkage of land-derived riverine waters with open ocean waters via 'buoyant plumes.' The project will assess the role of river discharge, tides and winds in the formation and maintenance of the buoyant plumes throughout the continental shelf. For such assessment, the project will use shipboard measurements, Autonomous Surface Vehicles, Autonomous flying vehicles (drones), and a floating platform that will be complemented by computer model simulations. The project will provide approximations of the linkage between land and open-ocean processes to be used in global-scale models. The project will also facilitate interactions between a research intensive university and an undergraduate college. It will train graduate students and provide valuable experiences to undergraduate students. This study concentrates on the dynamics of supercritical coastal buoyant plumes that expand obliquely across the shelf. These buoyant plumes transport low salinity waters across the continental shelf and can be entrained by ocean currents flowing by the shelf’s edge. The buoyant plumes are influenced by the balance between wind stress (upwelling-favorable) and buoyancy forcing. Tidal pulses of brackish water interfere with such dynamic balance to produce radial fronts referred to as sub-plumes. These sub-plumes are subsequently advected by Ekman transport. Data collection will consist of 4 seasonal surveys of Winyah Bay plume using ships (UNOLS ship requested), drones, Autonomous Surface Vehicles, and a floating platform to obtain profiles of water velocity, salinity, temperature, and turbulence properties. The sub-plume fronts shall be ubiquitous as long as the horizontal density gradient is prominent and the inertial period is greater than the tidal period. Observations will be complemented by numerical simulations with a non-hydrostatic numerical model. As Broader Impacts, the study will allow parametrization of cross-shelf plumes into lower resolution models that study land-ocean exchanges. The project will support 2 MS and 1 PhD students, and offer cruise opportunities to several undergraduate students. Data collected and their analysis will produce Ocean Data Analysis modules to be distributed to the oceanographic community. The project will be a collaboration between and R1 and a teaching institution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.