Seasonal cycle of hydrography on the eastern shelf of the <scp>F</scp>ilchner <scp>T</scp>rough, <scp>W</scp>eddell <scp>S</scp>ea, <scp>A</scp>ntarctica

Ryan, Svenja; Hattermann, Tore; Darelius, Elin; Schröder, Michael

doi:10.1002/2017jc012916

Cited by 45 publications

(85 citation statements)

References 39 publications

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“…The depth of the ISW layer does not seem to affect the periods of correlation, as we find significant correlation both during periods of thick ISW layer (e.g., October–December 2014) and thin ISW layer (e.g., April–June 2015, Figure b). Similar seasonal variability in the ISW layer thickness is also observed on the shelf east of the FT (Ryan et al, ) (Figure ), where it is accompanied by changes in the current direction.…”

Section: Resultssupporting

confidence: 78%

“…Here we present data from moorings on the upper eastern flank of the FT (ES1) and on the flat shelf, east of the FT (ES2), where a strong seasonality in both hydrography and circulation is observed (Ryan et al, ). Inflow of Modified Warm Deep Water (MWDW) occurs from January to June, when the thermocline at the shelf break is shallow (Årthun et al, ; Darelius et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…Dense water masses present on the shelf could also affect the southward transport of MWDW. In March–July, when the warm inflow is observed at ES1–2, the ISW layer does not reach the eastern shelf (Ryan et al, ). The thickness of the ISW layer could explain the seasonality of the flow direction in ES1–2.…”

Section: Discussionmentioning

confidence: 99%

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Wind Stress Mediated Variability of the Filchner Trough Overflow, Weddell Sea

et al. 2018

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The Filchner Trough (FT) is a key site for exchange of water masses between the Weddell Sea continental shelf and the deep ocean. Cold and dense Ice Shelf Water (ISW), a precursor for Antarctic Bottom Water, flows north along the FT and overflows the Filchner Sill. Although access of warm water to the Weddell Sea continental shelf is limited due to the presence of the Antarctic Slope Front, southward transport of warm water is facilitated through the FT. We use moored current meters from the Filchner Sill region to show that the monthly scale variability of the ISW overflow is connected to the variability of the alongslope wind stress upstream. Periods with significant correlation between the wind and ISW overflow are characterized by (I) wind directed along the continental slope, (II) high ISW overflow speed, and (III) high variability in the 16–64 day period band for wind and current. We propose that a recirculation of the slope current, associated with the Antarctic Slope Front, may occur in the FT during periods of strong wind forcing, and that such recirculation could explain the correlation between the wind stress and the ISW overflow. We further show that an increased wind stress along the continental slope leads to increased current speed within the slope current and the Antarctic Coastal Current, with possible implications for the on‐shore heat transport.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

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Wind Stress Mediated Variability of the Filchner Trough Overflow, Weddell Sea

et al. 2018

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“…During the sea ice peak period from July to September, the bottom box temperatures are low in the WS‐NIS (Figure a, mean temperature of

\overset{θ}{true}

= −1.89 ± 0.05 °C), the RS‐NIS (Figure i,

\overset{θ}{true} =

−1.87 ± 0.06 °C), and the WPB‐NIS (Figure c,

\overset{θ}{true} =

−1.86 ± 0.05 °C). For the same period, in the deeper bottom box, from 500 m and below, WS‐NIS temperatures are even lower (Figure S2a,

\overset{θ}{true} =

−2.11 ± 0.05 °C) and are indicative of ice shelf meltwater outflow occurring at the Filchner Ice Shelf edge, which is consistent with the observations made by Foldvik et al () and Ryan et al ().…”

Section: Bottom Box Seasonalitysupporting

confidence: 89%

Water Mass Characteristics of the Antarctic Margins and the Production and Seasonality of Dense Shelf Water

et al. 2019

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Conductivity-temperature-depth data from instrumented seals of the Marine Mammals Exploring Oceans from Pole to Pole program are analyzed to characterize the water masses and the seasonality of the marginal seas. Bottom temperatures are found to be in a cold regime in Dense Shelf Water (DSW) producing regions, identified in this study as the southern Weddell Sea, Cape Darnley, Prydz Bay, Adélie Coast, and the western Ross Sea. DSW occupies the bottom of the Weddell and Ross Sea continental shelves throughout the year: Production of DSW and vertical overturning occur only during the winter. In the other DSW producing regions, salinity is reduced more markedly during the summer. We identify the Princess Martha Coast, Leopold and Astrid Coast, and the Knox Coast as Low Salinity Shelf Water producing regions, where modified Circumpolar Deep Water (CDW) intrudes onto the continental shelf, reaching areas close to the ice shelves keeping the bottom temperatures in an intermediate regime.The Prince Harald Coast, the Amundsen Sea, and the Bellingshausen Sea experience more intense CDW intrusion, which keeps them in a warm regime year-round. CDW layer thicknesses correlate with the meridional winds over the shelf sea, and with the zonal winds at the slope, while DSW layer thicknesses correlate with the meridional winds over the shelf seas and the curl of the wind stress over the slope. Locations of DSW on the continental shelf coincide with an absence of warmer CDW near the ice shelves.

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“…The seasonal cycles of the wind stress and the surface heat and buoyancy fluxes suggest that the lateral heat advection across and along isobaths may be coupled to these forcings. Indeed, the water mass structure has been observed to have strong seasonal variability in several segments of the ACS, including the regions off the Adélie Coast in East Antartica (Snow et al, ) and the Central Amundsen (Wåhlin et al, ), East Amundsen (Mallett et al, ), Ross (Castagno et al, ), and East Weddell (e.g., Ryan et al, ) Seas. With the exception of the Adélie Coast, these regions show a greater presence of warm CDW‐influenced water on the shelf during summer and early fall.…”

Section: The Cross‐shelf Break Heat Transport Along the Antarctic Conmentioning

confidence: 99%

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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Seasonal cycle of hydrography on the eastern shelf of the Filchner Trough, Weddell Sea, Antarctica

Cited by 45 publications

References 39 publications

Wind Stress Mediated Variability of the Filchner Trough Overflow, Weddell Sea

Wind Stress Mediated Variability of the Filchner Trough Overflow, Weddell Sea

Water Mass Characteristics of the Antarctic Margins and the Production and Seasonality of Dense Shelf Water

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

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