Hydrography and circulation in the Filchner Depression, Weddell Sea, Antarctica

Darelius, Elin; Makinson, Keith; Daae, Kjersti; Fer, Ilker; Holland, Paul R.; Nicholls, Keith W.

doi:10.1002/2014jc010225

Cited by 35 publications

(57 citation statements)

References 51 publications

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“…The MGT draft, estimated to about 300 m at the MGT tip, was large enough, especially on the shallow Mertz Bank, to induce substantial shrinking of the water column and barotropic potential vorticity changes (Figure 12b). Similar arguments have been proposed by Darelius et al (2014) concerning the Filchner-Ronne Ice Shelf. From the MGT, the recirculation of the mCDW toward the sill was also constrained by the deep density distribution.…”

Section: Insight On the Shelf Dynamics Based On The Inverse Modelsupporting

confidence: 82%

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Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region

Martin¹,

Houssais²,

Goff³

et al. 2017

Deep Sea Research Part I: Oceanographic Research Papers

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The East Antarctic shelf off Adélie-George V Land is known to be an important region for Dense Shelf Water (DSW) formation as a result of intense sea ice production in the Mertz Glacier Polynya during the winter season. It is also a region where the warm modified Circumpolar Deep Water (mCDW) penetrates onto the shelf during the summer. Using hydrographic observations from a summer survey in 2008 we implement a box inverse model to propose a comprehensive view of the steady state circulation on this shelf in summer. Additional information from mooring observations collected on the depression slope is used to provide context to the retrieved circulation scheme. Over the depression slope, the summer baroclinic structure of the currents is found to contrast with the almost barotropic structure in winter.The summer circulation is strongly constrained by the DSW distribution and forms a clockwise circulation primarily transporting the fresh surface waters and the warm mCDW around the dome of DSW. Over the upper flank of the Mertz Bank, the inflow branch transports the mCDW towards the Mertz Glacier, while, over the lower part of the slope, the outflow branch returns to the sill a diluted mode of the same water mass. A total of 0.19 Sv of mCDW inflows at the sill and two-third reach the Mertz Glacier and recirculate in front of it, allowing the mCDW to penetrate into the deeper part of the depression. Possible scenarios of interaction between the mCDW and the DSW with the glacier are examined. It is shown that, despite the water mass pathways and transports suggest possible ice-ocean interaction, both lateral and basal melting were likely small in summer 2008. Finally, our results suggest that, in addition to bathymetric features, the distribution of the residual DSW which is left from the preceding winter sets up regional pressure gradients which provide a seasonal control on the shelf circulation. In particular, the spring collapse of the convective patch would contribute to setting up a deep pycnocline which strongly impacts the shelf circulation in the following summer, with possible feedback of the mCDW transports on the polynya activity and water mass formation.

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Section: Insight On the Shelf Dynamics Based On The Inverse Modelsupporting

confidence: 82%

“…Ha et al, 2014) or DSW production, such as the Weddell Sea (e.g. Carmack and Foster , 1975;Foldvik et al, 2001;Darelius et al, 2014) and the Ross Sea (e.g. Jacobs et al, 1970;Smith et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region

Martin¹,

Houssais²,

Goff³

et al. 2017

Deep Sea Research Part I: Oceanographic Research Papers

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“…In the trough, DSW flows along the eastern flank, crosses the sill to the western flank and leaves the trough (Figures a and c). The circulation in the trough is similar to recent observations and regional modeling of FD [ Darelius et al ., ], lending some credibility on the idealized model configuration.…”

Section: Resultsmentioning

confidence: 99%

On the effect of topography and wind on warm water inflow—An idealized study of the southern Weddell Sea continental shelf system

et al. 2017

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An idealized eddy‐resolving numerical model, with topographic features common to the southern Weddell Sea, is constructed to study mechanisms through which warm deep water enters a wide continental shelf with a trough. The open ocean, represented by a 1700 m deep channel, is connected to a 400 m deep shelf with a continental slope. The shelf is narrow (50 km) in the east but widens to 300 km at the center of the model domain. Over the narrow shelf, the slope front is balanced by wind‐driven Ekman downwelling and counteracting eddy overturning, favoring on‐shelf transport of warm water in summer scenarios when fresher surface water is present. Over the wide shelf, the Ekman downwelling ceases, and the mesoscale eddies relax the front. Inflow of warm water is sensitive to along‐shelf salinity gradients and is most efficient when denser water over the wide shelf favors up‐slope eddy transport along isopycnals of the V‐shaped slope front. Inflow along the eastern side of the trough cannot penetrate the sill region due to potential vorticity constraints, while along the western trough flank, eddy‐induced inflow crosses the sill and reaches the ice front. The warm inflow into the trough is sensitive to the density of the outflowing dense shelf water. For weaker winds, absence of the dense water outflow leads to a reversal of the trough circulation and a strong inflow of warm water, while for stronger winds, baroclinic effects become less important and the inflow is similar to experiments including dense water outflow.

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“…Modified Warm Deep Water (MWDW) enters the Filchner Trough at its eastern flank with a seasonal cycle, ranging from 0 • C during summer to −1.5 • C during winter (Årthun et al, 2012). Recent findings derived from CTDsections and mooring data by Darelius et al (2014) and modelling efforts by Makinson et al (2011) suggest that the classical view of a deep cyclonic circulation of Ice Shelf Water (ISW) (Carmack and Foster, 1975) might be revised into a flow which turns eastward, leaving the ice-shelf cavity, and crosses the sill at the eastern flank of the Filchner Trough.…”

Section: Ocean Modelmentioning

confidence: 99%

Future sea-level rise due to projected ocean warming beneath the Filchner Ronne Ice Shelf: A coupled model study

Thoma

Determann

Grosfeld

et al. 2015

Earth and Planetary Science Letters

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A general ocean circulation model is coupled with a 3D-thermodynamical ice-sheet/shelf model to simulate the response of the Filchner-Ronne Ice Shelf (FRIS, Antarctica) and coastal parts of its catchment basin to a postulated inflow of Warm Deep Water into the ice-shelf cavity on a 1000-yr timescale. Prescribed ocean warming (based on climate projections) enters the ice-shelf cavity in the up to 1500 m deep Filchner Trough and penetrates deep into the sub-ice cavity. Increasing basal melt rates induce geometry changes of the cavity, which in turn have an impact on the ocean circulation and therefore the modelled melt rates. Highest melt rates of about 20 m yr

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Hydrography and circulation in the Filchner Depression, Weddell Sea, Antarctica

Cited by 35 publications

References 51 publications

Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region

Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region

On the effect of topography and wind on warm water inflow—An idealized study of the southern Weddell Sea continental shelf system

Future sea-level rise due to projected ocean warming beneath the Filchner Ronne Ice Shelf: A coupled model study

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