Large-scale impacts of small-scale ocean topography

Article Mechanics

A generalized theory of flow forcing by rough topography

Timour Radko

Summary: An analytical model is developed to explore the impact of irregular sea-floor roughness on large-scale oceanic flows. The study systematically investigates the principal dissimilarities in the topographic regulation of slow and fast currents. It is found that fast flows are controlled by the Reynolds stresses produced by topographically generated eddies, while relatively weak flows are more affected by the eddy-induced bottom form drag. The combined asymptotic models for fast and slow currents provide a concise description of flow forcing by small-scale topography in homogeneous and multilayer models, which is validated through simulations.

JOURNAL OF FLUID MECHANICS (2023)

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Article Mechanics

Spin-down of a baroclinic vortex by irregular small-scale topography

Timour Radko

Summary: This study explores the impact of small-scale variability in the bottom relief on the dynamics and evolution of broad baroclinic flows in the ocean. The multiscale model reveals that bottom roughness affects circulation of vortices, making them more stable above rough topography.

JOURNAL OF FLUID MECHANICS (2022)

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Article Mechanics

Spin-down of a barotropic vortex by irregular small-scale topography

Timour Radko

Summary: This study examines the impact of small-scale irregular topographic features on the dynamics and evolution of large-scale barotropic flows in the ocean. A multiscale theory is developed to represent the large-scale effects of bottom roughness without explicitly resolving small-scale variability. The key mechanism of topographic control involves the generation of a small-scale eddy field associated with Reynolds stresses, which adversely affect mean circulation patterns. The accuracy of the multiscale model is remarkably high, even when scale separation is virtually non-existent.

JOURNAL OF FLUID MECHANICS (2022)

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Article Oceanography

The Impact of Representations of Realistic Topography on Parameterized Oceanic Lee Wave Energy Flux

L. E. Baker et al.

Summary: This study investigates the characteristics of lee waves in complex large scale topography areas using a realistic wave resolving simulation. The results show that spectral methods may not be suitable for rough topography areas, and a new method is proposed to effectively predict the lee wave energy flux.

JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS (2022)

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Article Oceanography

Parameterizing Nonpropagating Form Drag over Rough Bathymetry

Jody M. Klymak et al.

Summary: The study emphasizes the importance of internal drag from topography and proposes a simple parameterization scheme. Simulations show that the parameterization accurately predicts drag under different forcing parameters and replicates the effect of rough bathymetry on eddies in wind-driven channel flows.

JOURNAL OF PHYSICAL OCEANOGRAPHY (2021)

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Article Mechanics

Surface reflection of bottom generated oceanic lee waves

L. E. Baker et al.

Summary: This study demonstrates the potential importance of the surface in reflecting lee wave energy back into the interior using a linear model with viscosity and diffusivity. It shows that lee waves can interact with the upper ocean, resulting in enhanced vertical velocities and mixing near the surface under typical oceanic conditions.

JOURNAL OF FLUID MECHANICS (2021)

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Article Oceanography