Improved Internal Gravity Wave Spectral Continuum in a Regional Ocean Model

Arin Nelson, University of Colorado at Boulder, Atmospheric and Ocean Sciences, Boulder, CO, United States, Brian K Arbic, University of Michigan, Earth and Environmental Sciences, Ann Arbor, MI, United States, Dimitris Menemenlis, NASA Jet Propulsion Laboratory, Pasadena, United States, W Richard Peltier, Univ Toronto, Toronto, ON, Canada, Matthew H Alford, Scripps Institution of Oceanography, UC San Diego, La Jolla, United States, Nicolas Grisouard, University of Toronto, Physics, Toronto, ON, Canada, Jody M Klymak, University of Victoria, Victoria, BC, Canada and Yulin Pan, University of Michigan Ann Arbor, Ann Arbor, United States
Abstract:
This work summarizes recent advances in the understanding and skill of numerical ocean models in simulating the internal gravity wave spectral continuum as expected from observations and theory. Specifically, this work uses regional simulations of the MITgcm forced at the boundaries by a global 1/48-degree simulation previously used in the study of near-inertial waves and tides, LLC4320, at horizontal scales down to 250m and at triple the number of depth levels. Initial results show a dramatic improvement in the frequency spectral continuum, and a less dramatic improvement in the vertical wavenumber spectral continuum. Consistency relations are used for the first time on an ocean model output to verify that the variance in the spectra is in fact due to internal waves, and an application of wave-turbulence theory shows that induced diffusion is responsible for transferring energy from low-frequency modes via non-local interactions into the rest of the continuum.
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