Enhanced cross‐shelf exchange by tides in the western Ross Sea

Wang, Qiang; Danilov, Sergey; Hellmer, Hartmut; Sidorenko, Dmitry; Schröter, Jens; Jung, Thomas

doi:10.1002/2013gl058207

Cited by 38 publications

(49 citation statements)

References 30 publications

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“…We argue that the circulation over the Ross Sea continental shelf is predominantly geostrophic, driven by lateral density gradients induced through sea ice production, in particular in the polynyas. This supports Q. Wang et al () who attribute exchange flows near the shelf break to the intensification of CDW‐HSSW gradients. First, we explain the slowing circulation for higher wind stresses by increased mixing near the surface which leads to the production of less dense water in the model (Figure ).…”

Section: Results and Discussion: Sensitivity Experimentssupporting

confidence: 88%

The Density‐Driven Winter Intensification of the Ross Sea Circulation

et al. 2018

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The circulation over the Ross Sea continental shelf facilitates the exchange between the Southern Ocean and the Ross Ice Shelf cavity. Here transport and mixing processes control the access of oceanic heat from the Southern Ocean to the ice shelf base, the formation of sea ice, and the production of High Salinity Shelf Water (HSSW) in polynyas and hence the subsequent formation of Antarctic Bottom Water. A climatological ocean‐ice shelf coupled model of the Ross Sea Sector including the cavity, with prescribed sea ice fluxes, was used to examine the details of currents and their seasonal variability over the continental shelf. A system of two cyclonic and three anticyclonic persistent circulation features has been identified. Transports steadily increase throughout winter, with individual currents carrying up to 2 Sv, nearly doubling their minimum. The seasonal modulation is driven by lateral differences in density and subsequent baroclinic pressure gradients, induced through dense shelf water formation in the Ross Sea and the Terra Nova Bay Polynas. Wind plays a minor role in ocean momentum variability. Sensitivity experiments suggest a weakening of transports with increasing wind stress. Horizontal density variations at the ocean surface are smoothed by the wind. The source of momentum in the cavity is the gravity‐driven bottom flow of HSSW, produced in the Ross Sea Polynya as part of the thermohaline overturning circulation. Tracer experiments suggest that HSSW forming in the Terra Nova Bay Polynya has no cavity access, but instead is the main contributor to Antarctic Bottom Water formed in the northwest slope.

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Section: Results and Discussion: Sensitivity Experimentssupporting

confidence: 88%

The Density‐Driven Winter Intensification of the Ross Sea Circulation

et al. 2018

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“…As a result our model cannot represent the role of Antarctic gyre circulations and the Antarctic Circumpolar Current in shaping the ASF, relying solely on local surface wind forcing. Importantly, we have also neglected the influence of tidal mixing and transport, which is particularly pronounced on continental slopes and has been shown to induce a substantial shoreward transport of CDW in the western Ross Sea [Wang et al, 2013]. Despite these shortcomings, our model qualitatively captures the structure of the real ASF in various regions (see Figure 3).…”

Section: Discussionmentioning

confidence: 99%

Eddy‐mediated transport of warm Circumpolar Deep Water across the Antarctic Shelf Break

Stewart

Thompson

2015

Geophysical Research Letters

201

214

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The Antarctic Slope Front (ASF) modulates ventilation of the abyssal ocean via the export of dense Antarctic Bottom Water (AABW) and constrains shoreward transport of warm Circumpolar Deep Water (CDW) toward marine-terminating glaciers. Along certain stretches of the continental shelf, particularly where AABW is exported, density surfaces connect the shelf waters to the middepth Circumpolar Deep Water offshore, offering a pathway for mesoscale eddies to transport CDW directly onto the continental shelf. Using an eddy-resolving process model of the ASF, the authors show that mesoscale eddies can supply a dynamically significant transport of heat and mass across the continental shelf break. The shoreward transport of surface waters is purely wind driven, while the shoreward CDW transport is entirely due to mesoscale eddy transfer. The CDW flux is sensitive to all aspects of the model's surface forcing and geometry, suggesting that shoreward eddy heat transport may be localized to favorable sections of the continental slope.

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“…Tides also play a role in transporting and modifying CDW across the continental shelf and slope. For example, Wang et al () used a Ross Sea regional model to show that the export of DSW is partially counteracted by tidal shoreward transport of CDW, which mixes with and lightens the DSW, such that the DSW export is strongest at intermediate tidal amplitude. The tidal transfer of CDW may also impact shelf productivity by supplying iron to surface waters, though it appears that benthic sources are dominant in the Ross polynya (Mack et al, ).…”

Section: Dynamics and Variability Of The Ascmentioning

confidence: 99%

“…TRWs may be energized by tidal excursions across the continental slope (Foster et al, ; Middleton et al, ) or generated alongside mesoscale eddies by dense overflows (Lane‐Serff & Baines, ; Marques et al, ). TRWs may directly contribute to the steering of CDW onto warm continental shelves via troughs (St‐Laurent et al, ), but their importance relative to, for example, tides and coherent eddies (Couto et al, ; Wang et al, ), remains unknown. CTWs are generated by circum‐Antarctic and remote atmospheric variability (Kusahara & Ohshima, ), and the former has recently been identified as a mechanism of rapidly generating heat content anomalies along the WAP (Spence et al, ).…”

Section: Dynamics and Variability Of The Ascmentioning

confidence: 99%

The Antarctic Slope Current in a Changing Climate

Thompson

Stewart

Spence

et al. 2018

Reviews of Geophysics

271

330

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The Antarctic Slope Current (ASC) is a coherent circulation feature that rings the Antarctic continental shelf and regulates the flow of water toward the Antarctic coastline. The structure and variability of the ASC influences key processes near the Antarctic coastline that have global implications, such as the melting of Antarctic ice shelves and water mass formation that determines the strength of the global overturning circulation. Recent theoretical, modeling, and observational advances have revealed new dynamical properties of the ASC, making it timely to review. Earlier reviews of the ASC focused largely on local classifications of water properties of the ASC's primary front. Here we instead provide a classification of the current's frontal structure based on the dynamical mechanisms that govern both the along‐slope and cross‐slope circulation; these two modes of circulation are strongly coupled, similar to the Antarctic Circumpolar Current. Highly variable motions, such as dense overflows, tides, and eddies are shown to be critical components of cross‐slope and cross‐shelf exchange, but understanding of how the distribution and intensity of these processes will evolve in a changing climate remains poor due to observational and modeling limitations. Results linking the ASC to larger modes of climate variability, such as El Niño, show that the ASC is an integral part of global climate. An improved dynamical understanding of the ASC is still needed to accurately model and predict future Antarctic sea ice extent, the stability of the Antarctic ice sheets, and the Southern Ocean's contribution to the global carbon cycle.

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Enhanced cross‐shelf exchange by tides in the western Ross Sea

Cited by 38 publications

References 30 publications

The Density‐Driven Winter Intensification of the Ross Sea Circulation

The Density‐Driven Winter Intensification of the Ross Sea Circulation

Eddy‐mediated transport of warm Circumpolar Deep Water across the Antarctic Shelf Break

The Antarctic Slope Current in a Changing Climate

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