On the Origins of the Oceanic Ultraviolet Catastrophe
Abstract
We provide a firstprinciples analysis of the energy fluxes in the oceanic internal wave field. The resulting formula is remarkably similar to the renowned phenomenological formula for the turbulent dissipation rate in the ocean, which is known as the finescale parameterization. The prediction is based on the wave turbulence theory of internal gravity waves and on a new methodology devised for the computation of the associated energy fluxes. In the standard spectral representation of the wave energy density, in the twodimensional vertical wavenumberfrequency (mω) domain, the energy fluxes associated with the steady state are found to be directed downscale in both coordinates, closely matching the finescale parameterization formula in functional form and in magnitude. These energy transfers are composed of a “local” and a “scaleseparated” contributions; while the former is quantified numerically, the latter is dominated by the induced diffusion process and is amenable to analytical treatment. Contrary to previous results indicating an inverse energy cascade from high frequency to low, at odds with observations, our analysis of all nonzero coefficients of the diffusion tensor predicts a direct energy cascade. Moreover, by the same analysis fundamental spectra that had been deemed “noflux” solutions are reinstated to the status of “constantdownscaleflux” solutions. This is consequential for an understanding of energy fluxes, sources, and sinks that fits in the observational paradigm of the finescale parameterization, solving at once two longstanding paradoxes that had earned the name of “oceanic ultraviolet catastrophe.”
 Publication:

Journal of Physical Oceanography
 Pub Date:
 April 2022
 DOI:
 10.1175/JPOD210121.1
 arXiv:
 arXiv:2106.02572
 Bibcode:
 2022JPO....52..597D
 Keywords:

 Physics  Fluid Dynamics;
 Physics  Geophysics
 EPrint:
 20 pages, 8 figures