Incorporating Tides and Internal Gravity Waves within Global Ocean General Circulation Models
Brian Arbic, Professor, Department of Earth and Environmental Sciences, University of Michigan
Friday, March 31, 2023
Many oceanic motions are forced by its interaction with the atmosphere--winds generate waves and currents, air/sea heat exchange sets oceanic surface temperatures, and evaporation and precipitation set oceanic surface salinities. Aside from the atmosphere, the other primary forcing agent for the ocean is the gravitational potential of the Moon and Sun. However, until recently, high-resolution global modeling of tides has been done separately from high-resolution global modeling of the atmospherically-forced oceanic general circulation. Here we review the emerging class of high-resolution global models that are simultaneously forced by both atmospheric fields and the astronomical tidal potential. Such models simulate barotropic (surface) tides, internal tides, near-inertial motions, the eddying general oceanic circulation, and a partially resolved internal gravity wave continuum spectrum (Garrett-Munk spectrum) simultaneously. Internal gravity waves are waves with a gravitational restoring force that lie along the interfaces of layers of different density. They turn over and break just as surface wind waves do, and in so doing they mix the ocean interior. We review the technical aspects of global internal wave models and their myriad applications, for example, in satellite oceanography, operational oceanography, boundary forcing of regional models, tidal-cryosphere interactions, and assessment of future coastal flooding hazards in a changing climate with altered tides.
Brian Arbic is a professor of physical oceanography in the Department of Earth and Environmental Sciences at the University of Michigan. His group’s research, funded by NASA, DOE, NSF, and the Office of Naval Research, focuses on tides, internal gravity waves, mesoscale eddies, and the role of the ocean in weather and climate. Building upon his service in the US Peace Corps, Arbic founded the Coastal Ocean Environment Summer School In Nigeria and Ghana (COESSING; https://coessing.org), which has been running for one week in West Africa every year since 2015, and the Global Ocean Corps and Conveyor (https://globaloceancorps.org), a global effort to increase collaborations with oceanographers from less-resourced nations. The COESSING and Ocean Corps teams include many early career scientists and scientists from less-resourced nations. COESSING has been endorsed as a project of the UN Decade of Ocean Science for Sustainable Development, and Ocean Corps has been endorsed as a global programme of the Decade.