Ocean-Ice Shelf Interaction in East Antarctica

Silvano, Alessandro; Rintoul, Stephen R.; Herráiz‐Borreguero, Laura

doi:10.5670/oceanog.2016.105

Cited by 72 publications

(68 citation statements)

References 90 publications

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“…Recent studies in Prydz Bay propose that glacial meltwater from the nearby Amery Ice Shelf may bring a large, bioavailable source of dissolved iron from marine‐accredited ice beneath the ice shelf, locally enhancing primary productivity (Herraiz‐Borreguero et al, ). In contrast to the glacial meltwaters introduced by the intrusions of mCDW beneath the TIS and MUIS (warm‐regime) to Dalton Polynya, the glacial meltwaters introduced into Prydz Bay are the result of intrusions of cold Dense Shelf Water beneath the Amery Ice Shelf (cold regime; Silvano et al, ). The resulting outflow of supercooled ISW can entrain subglacial dissolved iron into the marine ice layer beneath the ice shelf and, upon basal melting, can deliver dissolved iron onto the continental shelf in concentrations up to 4 orders of magnitude higher than typical Southern Ocean waters (Herraiz‐Borreguero et al, ).…”

Section: Discussionmentioning

confidence: 99%

Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

Arroyo¹,

Shadwick

Tilbrook

2019

JGR Oceans

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The carbonate chemistry in the Dalton Polynya in East Antarctica (115°–123°E) was investigated in summer 2014/2015 using high‐frequency underway measurements of CO2 fugacity (fCO2) and discrete water column measurements of total dissolved inorganic carbon (TCO2) and total alkalinity. Air‐sea CO2 fluxes indicate this region was a weak net source of CO2 to the atmosphere (0.7 ± 0.9 mmol C m−2 day−1) during the period of observation, with the largest degree of surface water supersaturation (ΔfCO2 = +45 μatm) in ice‐covered waters near the Totten Ice Shelf (TIS) as compared to the ice‐free surface waters in the Dalton Polynya. The seasonal depletion of mixed‐layer TCO2 (6 to 51 μmol/kg) in ice‐free regions was primarily driven by sea ice melt and biological CO2 uptake. Estimates of net community production (NCP) reveal net autotrophy in the ice‐free Dalton Polynya (NCP = 5–20 mmol C m−2 day−1) and weakly heterotrophic waters near the ice‐covered TIS (NCP = −4–0 mmol C m−2 day−1). Satellite‐derived estimates of chlorophyll a (Chl a) and sea ice coverage suggest that the early summer season in 2014/2015 was anomalous relative to the long‐term (1997–2017) record, with lower surface Chl a concentrations and a greater degree of sea ice cover during the period of observation; the implications for seasonal primary production and air‐sea CO2 exchange are discussed. This study highlights the importance of both physical and biological processes in controlling air‐sea CO2 fluxes and the significant interannual variability of the CO2 system in Antarctic coastal regions.

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Section: Discussionmentioning

confidence: 99%

Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

Arroyo¹,

Shadwick

Tilbrook

2019

JGR Oceans

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“…This view is further supported by the similarities between the spatial structure of the observed trends in ice‐shelf thickness (Paolo et al, ) and water mass properties in the Weddell and Ross Seas and in West Antarctica: where ice shelves are thinning, both CDW and Antarctic Shelf Bottom Water are warming, and the CDW core on the adjacent continental slope is shoaling (Schmidtko et al, ). Further, recent observations in East Antarctica reveal that mCDW also reaches the Totten (Greenbaum et al, ; Rintoul et al, ; Silvano et al, ) and Moscow University (Silvano et al, ) ice shelves through deep cross‐shelf troughs, with sufficient heat content to induce melt rates comparable to those found in West Antarctica (Greenbaum et al, ; Rignot et al, ).…”

Section: Introductionmentioning

confidence: 95%

Oceanic Heat Delivery to the Antarctic Continental Shelf: Large‐Scale, Low‐Frequency Variability

2018

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Onshore penetration of oceanic water across the Antarctic continental slope (ACS) plays a major role in global sea level rise by delivering heat to the Antarctic marginal seas, thus contributing to the basal melting of ice shelves. Here the time‐mean (Φmean) and eddy (Φeddy) components of the heat transport (Φ) across the 1,000‐m isobath along the entire ACS are investigated using a 0.1∘ global coupled ocean/sea ice simulation based on the Los Alamos Parallel Ocean Program (POP) and sea ice (Community Ice CodE) models. Comparison with in situ hydrography shows that the model successfully represents the basic water mass structure, with a warm bias in the Circumpolar Deep Water layer. Segments of on‐shelf Φ, with lengths of O(100–1,000 km), are found along the ACS. The circumpolar integral of the annually averaged Φ is O(20 TW), with Φeddy always on‐shelf, while Φmean fluctuates between on‐shelf and off‐shelf. Stirring along isoneutral surfaces is often the dominant process by which eddies transport heat across the ACS, but advection of heat by both mean flow‐topography interactions and eddies can also be significant depending on the along‐ and across‐slope location. The seasonal and interannual variability of the circumpolarly integrated Φmean is controlled by convergence of Ekman transport within the ACS. Prominent warming features at the bottom of the continental shelf (consistent with observed temperature trends) are found both during high‐Southern Annular Mode and high‐Niño 3.4 periods, suggesting that climate modes can modulate the heat transfer from the Southern Ocean to the ACS across the entire Antarctic margin.

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“…They found that warm mCDW entered the TIS cavity through a deep trough at the calving front, the Totten Trough, and carried sufficient heat to sustain an area‐averaged basal melt rate >10 m yr −1 , in agreement with satellite observations [ Rignot et al ., ; Depoorter et al ., ; Liu et al ., ]. The TIS basal melt rate is the highest observed on the Sabrina Coast and the largest among the East Antarctic ice shelves with an area bigger than 1000 km 2 [ Silvano et al ., ]. Here we use an extended data set to show the spatial variability of the ocean properties on the continental shelf of the Sabrina Coast and to describe how ocean heat is transported to the MUIS and TIS.…”

Section: Introductionmentioning

confidence: 99%

Distribution of water masses and meltwater on the continental shelf near the Totten and Moscow University ice shelves

et al. 2017

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Warm waters flood the continental shelf of the Amundsen and Bellingshausen seas in West Antarctica, driving rapid basal melt of ice shelves. In contrast, waters on the continental shelf in East Antarctica are cooler and ice shelves experience relatively low rates of basal melt. An exception is provided by the Totten and Moscow University ice shelves on the Sabrina Coast, where satellite‐derived basal melt rates are comparable to West Antarctica. Recent oceanographic observations have revealed that relatively warm (∼−0.4°C) modified Circumpolar Deep Water (mCDW) enters the cavity beneath the Totten Ice Shelf through a 1100 m deep trough, delivering sufficient heat to drive rapid basal melt. Here we use observations from a recent summer survey to show that mCDW is widespread on the continental shelf of the Sabrina Coast, forming a warm (up to 0.3°C) and saline (34.5–34.6) bottom layer overlaid by cold (∼freezing point) and fresh (salinity ∼34.3) Winter Water. Dense Shelf Water is not observed. A 1000 deep m trough allows water at −1.3°C to reach the Moscow University ice‐shelf cavity to drive basal melt. Freshening by addition of glacial meltwater is widespread on the southern shelf at depths above 300–400 m, with maximum meltwater concentrations up to 4–5 ml L−1 observed in outflows from the ice‐shelf cavities. Our observations indicate that the ocean properties on the Sabrina Coast more resemble those found on the continental shelf of the Amundsen and Bellingshausen seas than those typical of East Antarctica.

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Ocean-Ice Shelf Interaction in East Antarctica

Cited by 72 publications

References 90 publications

Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

Oceanic Heat Delivery to the Antarctic Continental Shelf: Large‐Scale, Low‐Frequency Variability

Distribution of water masses and meltwater on the continental shelf near the Totten and Moscow University ice shelves

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