Impacts of Gulf Stream Warm-Core Rings on Gulf of Maine Circulation

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The Gulf of Maine is a marginal sea of critical ecological and economical importance. Influenced by both local and remote forcing, the Gulf of Maine physical and ecological system is currently experiencing rapid changes. The gulf undergoes significant water exchanges with the slope sea and the Scotian Shelf of distinct water masses. The slope waters are often found in the deep basins in the gulf and display a wide range of variability. Through modifying density distribution in the basins, the intruding slope waters can potentially alter the near-shore circulation and affect the along-shelf transport of marine species. Studying the water exchange between the Gulf of Maine and the slope sea is thus crucial for understanding the varying physical and ecological environment in the gulf, including the dynamics of reoccurring harmful algal blooms. This study aims to address the fundamental dynamics and regional influences of the interaction between the Gulf of Maine and Slope Sea on shorter time scales associated with Gulf Stream warm core rings. The outcome of this project will benefit coastal fisheries and public health and the work involves participation of high school and undergraduate students.Warm core rings are major events in the continental slope region. They interact with the unique topography at the Northeast Channel and affect the flow within the channel. Three possible modes of interactions between warm core rings and the Gulf of Maine are proposed: 1) A warm core ring drives outflow in the Northeast Channel as part of the offshore flowing streamer on the northeast side of the ring; 2) onshore motion of a ring limb causes intrusion of slope/ring waters into the channel; 3) a warm core ring pushes the shelf-slope front shoreward and enhances the generation of oscillatory exchange flows in the channel by along-shelf propagating frontal meanders. The study is based on two general hypotheses: 1) warm core rings activities in the adjacent slope sea induce strong flows in the Northeast Channel, resulting in significant heat and salt exchange between the Gulf of Maine and the slope sea; and 2) the warm core ring-induced inflow in the channel brings in dense slope waters and modulates the characteristics of the deep water masses and the coastal circulation in the Gulf of Maine. These hypotheses will be tested through the analysis of available in situ observations, satellite measurements, process-oriented idealized model simulations, and realistic regional model hindcast simulations.