Peculiarities of Dense Water Cascading off the Deep Part of Antarctic Continental Slope (A Case Study for the Commonwealth Sea)

Abstract At several locations around Antarctica, dense water is formed as a result of intense sea ice formation. When this dense water becomes sufficiently denser than the surrounding water, it descends the continental slope and forms Antarctic Bottom Water (AABW). This study presents the AABW formation off the coast of Cape Darnley [Cape Darnley Bottom Water (CDBW)] in East Antarctica, using a nonhydrostatic model. The model is forced for 8 months by a temporally uniform surface salt flux (because of sea ice formation) estimated from Advanced Microwave Scanning Radiometer for Earth Observing System (EOS; AMSR-E) data and a heat budget calculation. The authors reproduce AABW formation and associated periodic downslope flows of dense water. Descending pathways of dense water are largely determined by the topography; most dense water flows into depressions on the continental shelf, advects onto the continental slope, and is steered downslope to greater depths by the canyons. Intense sea ice formation is the most important factor in the formation of AABW off Cape Darnley, and the existence of depressions is of only minor importance for the flux of CDBW. The mechanism responsible for the periodic downslope flow of dense water is further analyzed using an idealized model setup. The period of dense water outflow is regulated primarily by the topographic beta effect.

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Dynamics of Dense Water Descending a Continental Slope*

Journal of Physical Oceanography ◽

10.1175/jpo2758.1 ◽

2005 ◽

Vol 35 (8) ◽

pp. 1318-1328 ◽

Cited By ~ 3

Author(s):

Hsien-Wang Ou

Keyword(s):

Continental Slope ◽

Mechanical Energy ◽

Frictional Torque ◽

Geostrophic Balance ◽

Friction Control ◽

Dense Water ◽

Density Anomaly ◽

Mass Properties ◽

Model Predictions ◽

Vorticity Balance

Abstract A reduced-gravity model is used to examine the dynamics of dense water descending a continental slope. The model solves for the geostrophically adjusted state before it is subjected to significant frictional decay. For such bottom-mounted flow, it is argued that frictional torque would dominate the net vorticity balance to equalize the edge flows, resulting in double velocity cores. Constrained by the geostrophic balance, the dense water thus may settle only over a concave bottom and is sheetlike, covering typically the whole slope rise. As such, the adjustment is characterized by a spreading rather than sinking of the layer—with little descent of the upper edge but a swift downslope current propelling the lower edge. Through the mechanical energy balance, it is found in addition that a greater density anomaly would increase the total entrainment flux to more strongly dilute the original anomaly, yielding a product water that is less varied in the water-mass properties. Model predictions compare favorably with some observed dense outflows, in support of the entrainment and friction control of the geostrophic adjustment.

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Controls on the formation and stability of gas hydrate-related bottom-simulating reflectors (BSRs): A case study from the west Svalbard continental slope

Journal of Geophysical Research Atmospheres ◽

10.1029/2007jb005200 ◽

2008 ◽

Vol 113 (B5) ◽

Cited By ~ 35

Author(s):

R. Ross Haacke ◽

Graham K. Westbrook ◽

Michael S. Riley

Keyword(s):

Continental Slope ◽

Gas Hydrate ◽

The West ◽

Bottom Simulating Reflectors

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Laboratory Experiments of Dense Water Descending on Continental Slope

Deep Ocean Circulation - Physical and Chemical Aspects - Elsevier Oceanography Series ◽

10.1016/s0422-9894(08)71335-7 ◽

1993 ◽

pp. 333-350 ◽

Cited By ~ 5

Author(s):

Yutaka Nagata ◽

Ryuji Kimura ◽

Hiroyuki Honji ◽

Yasuhiro Yamazaki ◽

Kazuhiro Kawaguchi ◽

...

Keyword(s):

Continental Slope ◽

Laboratory Experiments ◽

Dense Water

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Retraction Notice: Mapping Submarine Landslide: A Case Study in Northern Continental Slope of the South China Sea

The Open Petroleum Engineering Journal ◽

10.2174/1874834101609010328 ◽

2016 ◽

Vol 9 (1) ◽

pp. 328-328

Author(s):

Tianyun Su ◽

Xishuang Li ◽

Jiagang Li ◽

Lejun Liu

Keyword(s):

South China Sea ◽

Continental Slope ◽

South China ◽

Submarine Landslide ◽

The South China Sea ◽

The South ◽

China Sea ◽

Retraction Notice

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Can we quantitatively image complex structures with rays?

Geophysics ◽

10.1190/1.1444814 ◽

2000 ◽

Vol 65 (4) ◽

pp. 1223-1238 ◽

Cited By ~ 93

Author(s):

M. Stéphane Operto ◽

Sheng Xu ◽

Gilles Lambaré

Keyword(s):

Ray Tracing ◽

Quantitative Estimation ◽

Quantitative Imaging ◽

Complex Structures ◽

Deep Part ◽

Prestack Depth Migration ◽

Construction Technique ◽

Future Studies ◽

Depth Migration

Ray‐based prestack depth migration fails to image quantitatively complex structures when a single arrival—for example, the first or the strongest one—is taken into account. In this paper, we investigate whether accounting for multiple arrivals in ray‐based preserved amplitude prestack depth migration allows one to improve quantitative imaging of complex media. The asymptotic ray‐Born migration/inversion, originally designed to process one single arrival, is extended to the case of multiple arrivals by accounting for the cross‐contributions of all the source and receiver raypaths. Multiple arrivals in the folded ray fields are computed by a dynamic ray tracing based on a wavefront construction technique. With an application to the complex Marmousi model, we demonstrate that ray‐Born inversion can provide a reliable quantitative estimation of the relative impedance perturbation even in the complex deep part of the model, for which the amplitudes were underestimated drastically when only a single arrival was used, either the first or the strongest one. This 2-D case study shows that complex structures can be imaged quantitatively with rays. Future studies will require the optimizing of the implementation of ray‐Born migration/inversion with multiple arrivals before considering 3-D applications.

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