Icelandic Coastal Current interactions with peninsulas, bays, winds, and ocean currents controlling freshwater export and retention

The Icelandic Coastal Current is a buoyant (brackish) current that moves past coastal headlands and bays. This project will use the Icelandic Coastal Current as a case study to advance understanding of and quantify transport of water across the continental shelf caused by coastal land-forms, bottom variations, winds, and offshore flows. The project will draw information from drifting floats and computer simulations to track waters from the Icelandic Coastal Current. Computer simulations will also analyze the sensitivity of buoyant transport to shifts in river discharge variations associated with 21st and 22nd century warming. Simulations will track buoyant waters with artificial tracers that will provide information on the time it takes for these waters to flush out of the region. Simulations will leverage hydrographic observations by Iceland’s Marine & Freshwater Research Institute, and satellite measurements that distinguish the edge of the buoyant current. As broader impacts, the project will support one postdoctoral researcher and one graduate student. It will also incorporate findings into undergraduate and graduate classes, and post YouTube videos on river influences in the marine environment. The PI will participate in educational events at a public school system with a diverse student population. This study will examine freshwater export from Icelandic rivers to the North Atlantic Ocean. Iceland is the study region as it has an assortment of shelf conditions (e.g., wide and narrow shelf widths, high and low river input regions, extensive canyons and no canyons, headlands of different radii of curvature, upwelling and downwelling conditions) that allow exploration of a wide range of shelf-ocean interactions. In addition, the system is a gateway to the Arctic with a complex hydrological cycle (having river systems fed by glacial melt and precipitation) that are being impacted by climate change. Several specific objectives pertain to the offshore transport of coastal buoyant water in the presence of complex coastal topography, wind, and open ocean forcing. The research will address these objectives with doubly-nested realistic ROMS simulations with an outer resolution of 4km and an inner resolution of 0.5 km, and with drifter releases in the context of the buoyancy-driven Icelandic Coastal Current. Numerical simulations will be validated with data from Iceland’s Marine & Freshwater Research Institute and the drifter releases. Simulations will investigate different climate change scenarios focused on predicted changes in the hydrological cycle. Analyses will quantify shelf-ocean exchanges including tracer fluxes across the shelf break, calculations of Eddy Kinetic Energy fields, and residence times. 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.