The Dynamics behind Subinertial Variability along the Southeast Greenland Coast

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Oceanic circulation along the southeast Greenland coast has climate impacts of global significance. The spillage of dense water over the Denmark Strait sill into the main North Atlantic basin, contributes to a global circulation that distributes heat over the globe. In addition, warm water from the deep Atlantic basin intrudes into the cold fjords along the Greenland coast, where it melts glaciers and thus contributes to global sea level rise and potentially to changes in the regional ocean circulation. The intensity of these flows varies with a frequency of several days and the cause of this variability is not known. The main goal of this project is to determine the underlying dynamics causing this variability, and specifically the role played by waves known as coastal-trapped waves. Shedding light on what causes this dominant mode of variability, this work will aid to improve climate predictions and help design observational monitoring programs in the region. The results from this work will benefit physical oceanographers and climate scientists, as it will provide a fundamental understanding of variability in key climatic processes operating in Greenland. The project will support a female early career scientist, the training of a graduate student in numerical ocean modeling, and undergraduate student education through the development of individual research projects. Mid-depth and deep exchange flows along the southeast Greenland coast play a key role in the global climate system. Recent observational evidence of two such exchange flows (the deep Denmark Strait Overflow and fjord-shelf exchange in the mid-depth range) suggests that they are both governed by sub-inertial variability (time scale of several days). Furthermore, our preliminary results suggest that variability in the Denmark Strait Overflow and fjord-shelf exchange along the southeast Greenland coast are connected, which leads us to propose that they should be studied holistically. Despite sub-inertial variations being ubiquitous along the southeast Greenland coast, the underlying dynamics of these variations are not clear. We hypothesize that they are the imprint of coastal-trapped waves, and will study their properties, forcing mechanisms and impact on exchange flows using a combination of realistic high-resolution numerical model simulations and idealized process studies, synthesized with existing observations.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.