Form Drag and Mixing Due to Tidal Flow past a Sharp Point

Edwards, Kathleen A.; MacCready, Parker; Moum, James N.; Pawlak, Geno; Klymak, J. M.; Perlin, A.

doi:10.1175/1520-0485(2004)034<1297:fdamdt>2.0.co;2

Cited by 97 publications

(103 citation statements)

References 37 publications

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“…Thus, the observations downstream might potentially be the result of direct flow-obstacle interaction. There are strong similarities between the velocities, diffusivity and dissipation rates observed here and by Edwards et al (2004). Finescale modeling might elucidate the distribution and longevity of such mixing regions.…”

Section: Mixing Ratessupporting

confidence: 73%

“…Furthermore, sharp headlands strongly influence local flow through rectification of tides (e.g. Signell and Geyer, 1991;Edwards et al 2004). Although the EGT's elongated morphology is at the extreme end of the headland aspect ratio scale and glacier tongues are located at the surface rather than the bed, we expect there is much in common in terms of oceanic response to tidal flow.…”

Section: Generalization Conclusion and Future Workmentioning

confidence: 94%

“…In a situation with similar headland scale and flow speeds Edwards et al (2004) quantified how local turbulent buoyancy flux scaled with ε and that it is likely maximum very close to a headland. Recent modeling efforts (Dinniman et al, 2007;Reddy et al, 2010) that encompassed the region were at scales (>5 km) that are unlikely to be instantaneously influenced even by this degree of variability.…”

Section: Mixing Ratesmentioning

confidence: 99%

“…Although the EGT's elongated morphology is at the extreme end of the headland aspect ratio scale and glacier tongues are located at the surface rather than the bed, we expect there is much in common in terms of oceanic response to tidal flow. The headland work of Edwards et al (2004) identified the split between skin and form drag and that the majority of the diapycnal turbulent buoyancy flux occurred close by the headland. This supports the contention that more turbulence data very close to the glacier wall would help to identify the dynamic importance of such features.…”

Section: Generalization Conclusion and Future Workmentioning

confidence: 99%

“…The closest relevant work is that concerned with flow around headlands and islands (e.g. Edwards et al, 2004), except of course with a glacier tongue the flow can pass under the obstacle as well as around.…”

Section: Introductionmentioning

confidence: 99%

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Flow and mixing near a glacier tongue: a pilot study

et al. 2011

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Abstract.A glacier tongue floating in the coastal ocean presents a significant obstacle to the local flow and so influences oceanic mixing and transport processes. Here acoustic Doppler current profiler and shear microstructure observations very near to a glacier tongue side-wall capture flow accelerations and associated mixing. Flow speeds reached around 40 cm s −1 , twice that of the ambient tidal flow amplitude, and generated vertical velocity shear squared as large as 10 −5 s −2 . During the time of maximum flow, turbulent energy dissipation rates reached 10 −5 m 2 s −3 , around three decades greater than local background levels. This is in keeping with estimates of the gradient Richardson Number which dropped to ∼1 during maximum flow. Associated vertical diffusivities estimated from the shear microstructure results were substantial, reflecting the influence of the glacier on velocity gradients.

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Section: Mixing Ratessupporting

confidence: 73%

Section: Generalization Conclusion and Future Workmentioning

confidence: 94%

Section: Mixing Ratesmentioning

confidence: 99%

Section: Generalization Conclusion and Future Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flow and mixing near a glacier tongue: a pilot study

et al. 2011

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The influence of an Antarctic glacier tongue on near-field ocean circulation and mixing

Stevens

McPhee

Forrest

et al. 2014

J. Geophys. Res. Oceans

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In situ measurements of flow and stratification in the vicinity of the Erebus Glacier Tongue, a 12 km long floating Antarctic glacier, show the significant influence of the glacier. Three ADCPs (75, 300, and 600 kHz) were deployed close (<50 m) to the sidewall of the glacier in order to capture near-field flow distortion. Scalar (temperature and conductivity) and shear microstructure profiling captured small-scale vertical variability. and a background/residual flow ($4-10 cm s 21 ) flowing to the NW. Turbulence was dominated by deeper mixing during spring tide, likely indicative of the role of bathymetric variation which locally forms an obstacle as great as the glacier. During the neap tide, near-surface mixing was as energetic as that seen in the spring tide, suggesting the presence of buoyancy-driven near-surface flows. Estimates of integrated dissipation rate suggest that these floating extensions of the Antarctic ice sheet alter energy budgets through enhanced dissipation, and thus influence coastal near-surface circulation.

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The dynamics of pressure and form drag on a sloping headland: Internal waves versus eddies

Warner

MacCready

2014

J. Geophys. Res. Oceans

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Topographically generated eddies and internal waves have traditionally been studied separately even though bathymetry that creates both phenomena is abundant in coastal regions. Here a numerical model is used to understand the dynamics of eddy and wave generation as tidal currents flow past Three Tree Point, a 1 km long, 200 m deep, sloping headland in Puget Sound, WA. Bottom pressure anomalies due to vertical perturbations of the sea surface and isopycnals are used to calculate form drag in different regions of the topography to assess the relative importance of eddies versus internal waves. In regions where internal waves dominate, sea surface and isopycnal perturbations tend to work together to create drag, whereas in regions dominated by eddies, sea surface, and isopycnal perturbations tend to counteract each other. Both phenomena are found to produce similar amounts of form drag even though the bottom pressure anomalies from the eddy have much larger magnitudes than those created by the internal waves. Topography like Three Tree Point is common in high latitude, coastal regions, and therefore the findings here have implications for understanding how coastal topography removes energy from tidal currents.

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Form Drag and Mixing Due to Tidal Flow past a Sharp Point

Cited by 97 publications

References 37 publications

Flow and mixing near a glacier tongue: a pilot study

Flow and mixing near a glacier tongue: a pilot study

The influence of an Antarctic glacier tongue on near-field ocean circulation and mixing

The dynamics of pressure and form drag on a sloping headland: Internal waves versus eddies

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