Ocean mixing rates, distributions, mechanisms, impacts and representations from theoretical and observational perspectives

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Mixing is an important control on how the ocean functions; yet our understanding of ocean mixing is significantly limited by complex variability in mixing rates and processes and by a paucity of mixing measurements. The long-term objectives of this research program are to address measurement scarcity and advance our understanding of ocean mixing rates, space-time distributions, mechanisms, impacts and representations in ocean models. The flagship innovation of this program is the use of an instrumented underwater robot that provides near-continuous, sustained measurements of ocean turbulence and other water properties important to ocean physics, chemistry and biology, thus delivering unprecedented views of the ocean mixing environment. We also will apply turbulence parameterizations to mined data to understand the variability of ocean mixing more broadly, perform experiments with realistic ocean models to understand the impacts of mixing space-time geography on ocean state and functioning, and conduct theoretical studies to improve representations of mixing for next-generation ocean models. In this 5-year program, we will focus on 2 distinct regions of importance to Canada: the Beaufort Sea in the Arctic Ocean and the British Columbia coast. Our objectives are to: 1. exploit robotic observations of ocean turbulence to gain new insights into ocean mixing; 2. map mixing geography by applying mixing parameterizations to historical observations; 3. target the impact of mixing variability on Arctic Ocean state and its role in the climate system via experiments with Arctic Ocean models; and 4. develop frameworks for the parametrization of ocean mixing using theory and idealized modelling studies. Anticipated outcomes include new knowledge of ocean mixing rates, variability, mechanisms and impacts in our regions of focus, and a better appreciation of the limitations of current model mixing prescriptions and ways that they could be improved. These efforts will also build capacity for robotic ocean observing in Canada's oceans, connect the observational and modelling communities, and train 14 HQP in an environment committed to inclusion. This research is critical and urgent to improve our understanding of how our marine systems function, as well as the numerical models of these systems that we rely on to make predictions of future environmental change. Benefits to the field include the provision of novel, highly-resolved and multidisciplinary datasets, and an improved understanding of mixing rates and mechanisms that can be applied to urgent research questions in multiple disciplines of ocean science. Benefits to Canada include the provision of information and system understanding critical for sustainable development and climate change adaptation in Canada's coastal waters, as well as the strengthening of Canada's standing in the international science community by being at the forefront of ocean observing technology and the science it enables.