Volume transport of the <scp>A</scp>ntarctic <scp>C</scp>ircumpolar <scp>C</scp>urrent: Production and validation of a 20 year long time series obtained from in situ and satellite observations

Koenig, Zoé; Provost, Christine; Ferrari, Ramiro; Sennéchael, Nathalie; Rio, Marie-Hélène

doi:10.1002/2014jc009966

Cited by 51 publications

(104 citation statements)

References 44 publications

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“…Volume transport through Drake Passage over the last 5 years (and also over the entire 10 years) of the simulation is 143 6 10 Sv (1 Sv 5 10 6 m 3 s 21 ), which matches quite well with the mean and variability of observational estimates of 134 6 11 Sv (Cunningham et al 2003) and 141 6 13 Sv (Koenig et al 2014). The ACC volume transport is likely important to on-shelf heat transport, especially where the ACC impinges on the shelf break (e.g., Amundsen-Bellingshausen sector), as fully eddy-resolving models have shown a relationship between the shelf-break jet speed and the on-shelf heat transport (e.g., St-Laurent et al 2013).…”

Section: A Era-int Simulation Of the Southern Ocean And Ice Shelf Basupporting

confidence: 66%

The Effect of Atmospheric Forcing Resolution on Delivery of Ocean Heat to the Antarctic Floating Ice Shelves*,+

et al. 2015

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Oceanic melting at the base of the floating Antarctic ice shelves is now thought to be a more significant cause of mass loss for the Antarctic ice sheet than iceberg calving. In this study, a 10-km horizontal-resolution circum-Antarctic ocean-sea ice-ice shelf model [based on the Regional Ocean Modeling System (ROMS)] is used to study the delivery of ocean heat to the base of the ice shelves. The atmospheric forcing comes from the ERA-Interim reanalysis (;80-km resolution) and from simulations using the polar-optimized Weather Research and Forecasting Model (30-km resolution), where the upper atmosphere was relaxed to the ERAInterim reanalysis. The modeled total basal ice shelf melt is low compared to observational estimates but increases by 14% with the higher-resolution winds and just 3% with both the higher-resolution winds and atmospheric surface temperatures. The higher-resolution winds lead to more heat being delivered to the ice shelf cavities from the adjacent ocean and an increase in the efficiency of heat transfer between the water and the ice. The higher-resolution winds also lead to changes in the heat delivered from the open ocean to the continental shelves as well as changes in the heat lost to the atmosphere over the shelves, and the sign of these changes varies regionally. Addition of the higher-resolution temperatures to the winds results in lowering, primarily during summer, the wind-driven increase in heat advected into the ice shelf cavities due to colder summer air temperatures near the coast.

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Section: A Era-int Simulation Of the Southern Ocean And Ice Shelf Basupporting

confidence: 66%

The Effect of Atmospheric Forcing Resolution on Delivery of Ocean Heat to the Antarctic Floating Ice Shelves*,+

et al. 2015

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“…However, the few available vertical current strength profiles from the CHC show that the high velocities reach down to >2,000-m water depth (23), and we, therefore, do not expect large modifications of the vertical flow structure at our site since the last glacial. Alternatively, the northern DP record from core MR0806-PC09 might underestimate the glacial flow decrease because of the rather complex flow geometry with major eddy structures in this region (6,9,30). Taken together, qualitatively, our two sediment core records uniformly document a substantial decrease in sub-Antarctic CHC/ northern ACC flow speeds upstream and within the DP.…”

Section: Resultsmentioning

confidence: 61%

“…Modern oceanography suggests that current velocities and transport are overall closely linked in the DP region, with the major transport and the highest current velocities occurring in the sub-Antarctic Zone (Fig. 2B) (5,6,9). Therefore, we interpret our paleodata in terms of a substantial LGM decrease of sub-Antarctic DP throughflow combined with an additional slight reduction of ACC transport in the glacially extended sea ice zone (13).…”

Section: Resultsmentioning

confidence: 77%

“…If applicable to modern timescales, the strengthening and poleward shift of the SWW seen in the Coupled Model Intercomparison Project Phase 5 (7) might lead to a future increase in subAntarctic DP transport, strengthening of the ACC, and enhanced interbasin exchange. However, recent instrumental volume transport time series across the DP have not yet revealed any significant increase in response to strengthened westerly winds (6). Thus, the response of the ACC to future climate changes remains a major challenge to be addressed.…”

Section: Discussionmentioning

confidence: 99%

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Glacial reduction and millennial-scale variations in Drake Passage throughflow

Lamy

Arz

Kilian

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

113

111

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The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through this gateway is, therefore, crucial for advancing our understanding of the Southern Ocean’s role in global ocean and climate variability. Here, we reconstruct changes in DP throughflow dynamics over the past 65,000 y based on grain size and geochemical properties of sediment records from the southernmost continental margin of South America. Combined with published sediment records from the Scotia Sea, we argue for a considerable total reduction of DP transport and reveal an up to ∼40% decrease in flow speed along the northernmost ACC pathway entering the DP during glacial times. Superimposed on this long-term decrease are high-amplitude, millennial-scale variations, which parallel Southern Ocean and Antarctic temperature patterns. The glacial intervals of strong weakening of the ACC entering the DP imply an enhanced export of northern ACC surface and intermediate waters into the South Pacific Gyre and reduced Pacific–Atlantic exchange through the DP (“cold water route”). We conclude that changes in DP throughflow play a critical role for the global meridional overturning circulation and interbasin exchange in the Southern Ocean, most likely regulated by variations in the westerly wind field and changes in Antarctic sea ice extent.

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“…The canonical value of 134 Sv (± 11.2 Sv), obtained by Cunningham et al (2003) after reviewing ISOS data deployed from January 1979 to February 1980 (Whitworth and R. 1985), is however widely utilized by the physical oceanography community. More recent estimations with a method combining moorings and altimeter 1993-2012 measurements (Koenig et al 2014) also give a total net transport of 140 Sv (± 10 Sv).…”

Section: Liquid Ocean Transportsmentioning

confidence: 96%

An assessment of ten ocean reanalyses in the polar regions

et al. 2018

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Global and regional ocean and sea ice reanalysis products (ORAs) are increasingly used in polar research, but their quality remains to be systematically assessed. To address this, the Polar ORA Intercomparison Project (Polar ORA-IP) has been established following on from the ORA-IP project. Several aspects of ten selected ORAs in the Arctic and Antarctic were addressed by concentrating on comparing their mean states in terms of snow, sea ice, ocean transports and hydrography. Most polar diagnostics were carried out for the first time in such an extensive set of ORAs. For the multi-ORA mean state, we found that deviations from observations were typically smaller than individual ORA anomalies, often attributed to offsetting biases of individual ORAs. The ORA ensemble mean therefore appears to be a useful product and while knowing its main deficiencies and recognising its restrictions, it can be used to gain useful information on the physical state of the polar marine environment.

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Volume transport of the Antarctic Circumpolar Current: Production and validation of a 20 year long time series obtained from in situ and satellite observations

Cited by 51 publications

References 44 publications

The Effect of Atmospheric Forcing Resolution on Delivery of Ocean Heat to the Antarctic Floating Ice Shelves*,+

The Effect of Atmospheric Forcing Resolution on Delivery of Ocean Heat to the Antarctic Floating Ice Shelves*,+

Glacial reduction and millennial-scale variations in Drake Passage throughflow

An assessment of ten ocean reanalyses in the polar regions

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