A seasonal cycle in the export of bottom water from the Weddell Sea

Gordon, Arnold L.; Huber, Bruce A.; McKee, Darren C.; Visbeck, Martin

doi:10.1038/ngeo916

Cited by 71 publications

(100 citation statements)

References 26 publications

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“…This can be considered as evidence supporting the suggestion of FB01: the wind induced variability in the gyre circulation over the bottom plume has very significant impact on the plume variability. Although the variability of shelf water export rates and the corresponding driving mechanisms in different regions (including the southern, southwestern and western Weddell Sea) can be different [e.g., Gordon et al, 2010;McKee et al, 2011], all contributions to WSBW can be similarly influenced by the barotropic gyre velocity along their propagation pathway, leading to the observed mean WSBW seasonality in the northern Weddell Sea: colder in austral fall and warmer in austral spring [FB01; Gordon et al, 2010]. We speculate that the mechanisms driving the WSBW transport variability described in this paper also apply on interannual and longer time scales, which needs to be verified in future work.…”

Section: Discussionmentioning

confidence: 99%

“…[3] Strong variability on both annual and interannual scales has been observed in the WSBW properties near the Antarctic Peninsula (AP) tip [Fahrbach et al, 2001, hereinafter FB01] and southeast of the South Orkney Islands [Gordon et al, 2010]. By examining the current velocity from moorings, FB01 suggest that the observed variations are due to fluctuations in WSBW formation rates and fluctuations related to the large-scale Weddell gyre circulation.…”

Section: Introductionmentioning

confidence: 99%

“…By examining the current velocity from moorings, FB01 suggest that the observed variations are due to fluctuations in WSBW formation rates and fluctuations related to the large-scale Weddell gyre circulation. Gordon et al [2010] propose that the seasonal fluctuations of WSBW properties are governed by the seasonal cycle of winds over the western margin of the Weddell Sea. It is speculated that winds can influence both the production of HSSW and its access to the continental slope in the southwestern Weddell Sea, thus the bottom plume variability observed downstream [Gordon et al, 2010;McKee et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

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On the impact of wind forcing on the seasonal variability of Weddell Sea Bottom Water transport

Wang

Danilov

Fahrbach

et al. 2012

Geophysical Research Letters

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[1] The seasonal variability of Weddell Sea Bottom Water (WSBW) transport and its driving mechanisms are examined using FESOM simulations. Pronounced seasonal variability is present in both the Filchner shelf water export rate and the WSBW transport rate near the Antarctic Peninsula (AP) tip. The variabilities at both locations are linked to the surface wind forcing. The Filchner shelf water export rate responds to the onshore propagating density anomaly, which is caused by the wind-induced variation of the isopycnal depression at the coast. The variability near the AP tip originates from upstream variations at the Filchner Depression and from seasonal variability of the Weddell gyre strength.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the impact of wind forcing on the seasonal variability of Weddell Sea Bottom Water transport

Wang

Danilov

Fahrbach

et al. 2012

Geophysical Research Letters

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“…Relatively warm circumpolar deep water (CDW) is transported by the Weddell Gyre from the Antarctic Circumpolar Current (ACC) southwards along the eastern boundary into the Weddell Sea and mixes with cold surface waters generating warm deep water (WDW) (e.g. Orsi et al, 1993;Gordon et al, 2010). Through heat loss and mixing primarily during winter with winter water (WW) when flowing further to the west along the continental margin, WDW becomes modified warm deep water (MWDW).…”

Section: Study Area and Regional Oceanographymentioning

confidence: 99%

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

et al. 2014

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Abstract. The Weddell Sea and the associated FilchnerRønne Ice Shelf constitute key regions for global bottomwater production today. However, little is known about bottom-water production under different climate and icesheet conditions. Therefore, we studied core PS1795, which consists primarily of fine-grained siliciclastic varves that were deposited on contourite ridges in the southeastern Weddell Sea during the Last Glacial Maximum (LGM). We conducted high-resolution X-ray fluorescence (XRF) analysis and grain-size measurements with the RADIUS tool (Seelos and Sirocko, 2005) using thin sections to characterize the two seasonal components of the varves at sub-mm resolution to distinguish the seasonal components of the varves.Bright layers contain coarser grains that can mainly be identified as quartz in the medium-to-coarse silt grain size. They also contain higher amounts of Si, Zr, Ca, and Sr, as well as more ice-rafted debris (IRD). Dark layers, on the other hand, contain finer particles such as mica and clay minerals from the chlorite and illite groups. In addition, Fe, Ti, Rb, and K are elevated. Based on these findings as well as on previous analyses on neighbouring cores, we propose a model of enhanced thermohaline convection in front of a grounded ice sheet that is supported by seasonally variable coastal polynya activity during the LGM. Accordingly, katabatic (i.e. offshore blowing) winds removed sea ice from the ice edge, leading to coastal polynya formation. We suggest that glacial processes were similar to today with stronger katabatic winds and enhanced coastal polynya activity during the winter season. Under these conditions, lighter coarser-grained layers are likely glacial winter deposits, when brine rejection was increased, leading to enhanced bottom-water formation and increased sediment transport. Vice versa, darker finer-grained layers were then deposited during less windier season, mainly during summer, when coastal polynya activity was likely reduced.

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“…Since 1999, Gordon has maintained an array of moorings in the Weddell Sea, one of the main areas where cold surface waters sink to form ocean bottom currents. He has seen the deep water growing less salty in some areas, but the long-term trends are not clear 6 .…”

Section: "The Southern Ocean Is Doing Us a Big Favour At The Moment mentioning

confidence: 99%

How much longer can Antarctica’s hostile ocean delay global warming?

Tollefson¹

2016

Nature

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A seasonal cycle in the export of bottom water from the Weddell Sea

Cited by 71 publications

References 26 publications

On the impact of wind forcing on the seasonal variability of Weddell Sea Bottom Water transport

On the impact of wind forcing on the seasonal variability of Weddell Sea Bottom Water transport

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

How much longer can Antarctica’s hostile ocean delay global warming?

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