Circum‐Antarctic Shoreward Heat Transport Derived From an Eddy‐ and Tide‐Resolving Simulation

Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris

doi:10.1002/2017gl075677

Cited by 100 publications

(179 citation statements)

References 77 publications

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“…Moreover, small‐scale features on the Antarctic slope are not well resolved by our model. Therefore, processes like eddies (Stewart & Thompson, ), waves (St‐Laurent et al, ), tidal fluctuations (Stewart et al, ), and the dynamics of jets forming on the slope (Peña‐Molino et al, ; Thompson & Heywood, ) are not well captured in our study and they can influence cross‐shelf exchange. Nevertheless, the consistency between observations and modeling results in our study suggests that seasonal variability of the flow on the Antarctic slope regulates the seasonality of the MCDW intrusions onto the Sabrina Coast continental shelf.…”

Section: Discussionmentioning

confidence: 85%

“…The interaction between currents on the upper slope and troughs at the shelf break is not the only mechanism that can drive cross‐shelf exchange. Other processes can also be important, including waves on the upper slope (St‐Laurent et al, ), tidal fluctuations (Stewart et al, ), curvature of the isobaths (Dinniman et al, ), and eddy fluxes (Nøst et al, ; Stewart & Thompson, ; Thompson et al, ). These processes can be especially important in regions where topographic depressions are absent at the shelf break and a geostrophic flow along isobaths cannot support MCDW access to the continental shelf (Stewart et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Seasonality of Warm Water Intrusions Onto the Continental Shelf Near the Totten Glacier

et al. 2019

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Warm Modified Circumpolar Deep Water (MCDW) from the Southern Ocean drives rapid basal melt of the Totten Ice Shelf on the Sabrina Coast (East Antarctica), affecting the mass balance of the grounded Totten Glacier. Recent observations show that MCDW intrudes onto the continental shelf through a depression at the shelf break. Here we investigate such intrusions by combining (1) new oceanographic and bathymetric observations collected for two consecutive years by profiling floats in the depression south of the shelf break, (2) oceanographic measurements collected by conductivity‐temperature‐depth‐instrumented seals on continental slope, and (3) an ocean model. The depression provides a pathway for persistent inflow of warm (0‐1°C) MCDW to the inner shelf. In austral autumn and early winter MCDW intrusions were up to 0.5°C warmer and were ~75 m thicker than in spring and summer. The seasonality of the flow on the continental slope explains the seasonality of the intrusions. The MCDW layer on the continental slope is warmer and thicker to the east of the depression than to the west. In autumn and early winter a strong, top‐to‐bottom westward current (Antarctic Slope Current) transports the warmer and thicker MCDW layer along the slope and is diverted poleward at the eastern entrance of the depression. A bottom‐intensified eastward current (Antarctic Slope Undercurrent) develops in other months, allowing cooler and thinner intrusions to enter the depression from the west. Our study illustrates how circulation on the Antarctic slope regulates the ocean heat delivery to the continental shelf and ultimately to the ice shelves.

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Section: Discussionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Seasonality of Warm Water Intrusions Onto the Continental Shelf Near the Totten Glacier

et al. 2019

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“…The current state of understanding is that both tides and eddies are significant in effecting cross‐shelf exchange (Nøst et al, ; A.F. Thompson et al, ; Stewart et al, ; see also section ), with onshore eddy and Ekman‐driven transports being balanced by offshore near‐bottom flows. However, most of this understanding comes from numerical simulations (both realistic and idealized).…”

Section: Physical Oceanographymentioning

confidence: 99%

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

124

147

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The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures, and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide, and global modeling efforts—thereby enhancing predictions of the WG in global ocean circulation and climate.

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“…A series of realistic ocean models illustrate the importance of eddy‐mediated heat transfer onto the continental shelf in East Antarctica (Hattermann et al, ), the Amundsen Sea (Nakayama et al, ; St‐Laurent et al, ), the west Antarctic Peninsula (Graham et al, ), and Prydz Bay (Liu et al, ). A comprehensive modeling study of on‐shelf heat transport around Antarctica found that eddies drive the net shoreward heat transport onto the continental shelves (Stewart et al, ).…”

Section: Introductionmentioning

confidence: 99%

Modeling Ocean Eddies on Antarctica's Cold Water Continental Shelves and Their Effects on Ice Shelf Basal Melting

et al. 2019

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Changes in the rate of ocean‐driven basal melting of Antarctica's ice shelves can alter the rate at which the grounded ice sheet loses mass and contributes to sea level change. Melt rates depend on the inflow of ocean heat, which occurs through steady circulation and eddy fluxes. Previous studies have demonstrated the importance of eddy fluxes for ice shelves affected by relatively warm intrusions of Circumpolar Deep Water. However, ice shelves on cold water continental shelves primarily melt from dense shelf water near the grounding line and from light surface water at the ice shelf front. Eddy effects on basal melt of these ice shelves have not been studied. We investigate where and when a regional ocean model of the Ross Sea resolves eddies and determine the effect of eddy processes on basal melt. The size of the eddies formed depends on water column stratification and latitude. We use simulations at horizontal grid resolutions of 5 and 1.5 km and, in the 1.5‐km model, vary the degree of topography smoothing. The higher‐resolution models generate about 2–2.5 times as many eddies as the low‐resolution model. In all simulations, eddies cross the ice shelf front in both directions. However, there is no significant change in basal melt between low‐ and high‐resolution simulations. We conclude that higher‐resolution models (<1 km) are required to better represent eddies in the Ross Sea but hypothesize that basal melt of the Ross Ice Shelf is relatively insensitive to our ability to fully resolve the eddy field.

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Circum‐Antarctic Shoreward Heat Transport Derived From an Eddy‐ and Tide‐Resolving Simulation

Cited by 100 publications

References 77 publications

Seasonality of Warm Water Intrusions Onto the Continental Shelf Near the Totten Glacier

Seasonality of Warm Water Intrusions Onto the Continental Shelf Near the Totten Glacier

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Modeling Ocean Eddies on Antarctica's Cold Water Continental Shelves and Their Effects on Ice Shelf Basal Melting

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