Published In
Ocean Modelling
Document Type
Post-Print
Publication Date
2-2026
Subjects
Internal lee waves, Direct numerical simulations, Energy budgets
Abstract
Internal lee waves generated by the interaction between geostrophic flows and ocean-floor topography are recognized as an important pathway for transferring energy from large-scale circulation to small-scale mixing in the deep ocean; however, energy fluxes inferred from field observations often fall well below estimates based on classical linear theory. Here, we use direct numerical simulations to examine how three-dimensional (3D) topographic structure alters the generation and energy pathways of internal lee waves. We simulated idealized stratified flows impinging on twodimensional (2D) and 3D sinusoidal topography in a radiating regime. We used Reynolds decomposition based on spatial averaging to isolate wave-induced motion, and we quantified the energetics of lee waves through a detailed analysis of the wave kinetic energy budget. In a non-rotating reference frame, we find that the transition from 2D to 3D topography leads to a significant reduction in lee-wave generation, with vertically integrated wave kinetic energy generation decreasing by a factor of 5–15. This reduction can be attributed primarily to a strong suppression of pressure work, while shear production associated with nonlinear processes becomes the dominant source of wave energy. When rotation is included, the total wave energy generation shows no similar reduction between 2D and 3D configurations; nevertheless, shear production contributes >50% of the total generation over 3D topography. These results demonstrate that 3D topography fundamentally reshapes the energy pathways of internal lee waves by increasing nonlinear contributions, thereby providing a physical explanation for the systematic overestimation of lee-wave energetics by linear theory in realistic oceanic settings.
Rights
Copyright 2026 The Authors, Licensed under CC BY-NC-ND 4.0
Locate the Document
DOI
10.1016/j.ocemod.2026.102719
Persistent Identifier
https://archives.pdx.edu/ds/psu/44529
Citation Details
H. H. Xu, X. Zhu, and K. Zheng, “Three-dimensional topographical effects on the generation of internal lee waves,” Ocean Modeling, vol. 201, p. 102719, 2026.
Description
This is the accepted manuscript version subsequently published by Elsevier, made available after a 24 month embargo.