- 1Department of Physics, University of Toronto, Toronto, Ontario, Canada
- 2Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- 3Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- 4Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
- 5Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, MI, USA
- 6Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Internal wave dynamics play a critical role in understanding ocean diapycnal diffusivity and associated mixing processes, particularly in the deep ocean context. Building upon prior analyses of internal wave breaking and its influence on diapycnal diffusivity, in this study we employ a high-resolution regional ocean model to infer ocean diapycnal diffusivity due to internal wave (IW) breaking [Momeni et al., 2025]. Our work leverages the Bouffard-Boegman parameterization, which distinguishes between reversible and irreversible mixing components. This framework provides a robust methodology to infer diapycnal diffusivity profiles from turbulent dissipation rates, improving upon earlier KPP-based approaches that lacked this critical distinction. This inference is made possible through the work of Skitka et al. [2024], which directly measured dissipation rates from numerical simulations.
The findings reinforce and expand on earlier results from dynamically downscaled simulations in the northeast Pacific, which revealed a pronounced wave-turbulence cascade and highlighted the suppression of higher-order IW modes due to the background component of KPP. By deactivating this component, higher-order modes engage in triad resonance interactions with lower-order modes and are effectively energized; they subsequently undergo shear instability, enhancing mixing rates and aligning diffusivity profiles with empirical observations. This mechanism is discussed in detail in Momeni et al. [2024].
Our results underscore KPP’s limitations in distinguishing mixing processes and its tendency to overestimate shear contributions to diffusivity. These insights pave the way for improving diapycnal diffusivity parameterizations in low-resolution climate models by emphasizing mechanisms rooted in internal wave breaking rather than simplified parameterizations. Future work will focus on higher-resolution simulations to refine these findings and address basin- and latitude-dependent variations.
References
Kayhan Momeni, Yuchen Ma, William R Peltier, Dimitris Menemenlis, Ritabrata Thakur, Yulin Pan, Brian K Arbic, Joseph Skitka, and Matthew H Alford. Breaking internal waves and ocean diapycnal diffusivity in a high-resolution regional ocean model: Evidence of a wave-turbulence cascade. Journal of Geophysical Research: Oceans, 129(6):e2023JC020509, 2024.
Kayhan Momeni, W Richard Peltier, Joseph Skitka, Yuchen Ma, Brian K Arbic, Dimitris Menemenlis, and Yulin Pan. An alternative buoyancy reynolds number-based inference of ocean diapycnal diffusivity due to internal wave breaking: results from a high-resolution regional ocean model. Geophysical Research Letters, 2025. Submitted for publication.
Joseph Skitka, Brian K Arbic, Yuchen Ma, Kayhan Momeni, Yulin Pan, William R Peltier, Dimitris Menemenlis, and Ritabrata Thakur. Internal-wave dissipation mechanisms and vertical structure in a high-resolution regional ocean model. Geophysical Research Letters, 51(17):e2023GL108039, 2024.
How to cite: Momeni, K., Peltier, W. R., Skitka, J., Ma, Y., Arbic, B. K., Pan, Y., and Menemenlis, D.: Wave-Turbulence Cascades and Deep Ocean Mixing: Inferring Diapycnal Diffusivity in High-Resolution Ocean Models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4591, https://doi.org/10.5194/egusphere-egu25-4591, 2025.
