Effect of wind changes during the Last Glacial Maximum on the circulation in the Southern Ocean

Klinck, John M.; Smith, Dale

doi:10.1029/93pa01046

Cited by 33 publications

(21 citation statements)

References 17 publications

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“…UCDW is a warm (1°–2°C), saline (34.6–34.7 psu), nutrient‐rich, ACC intermediate water mass comprised of recirculated Pacific Ocean, Indian Ocean, and modified NADW waters [ Jacobs et al , 1985; Smith et al , 1998a]. The presence of UCDW in Palmer Deep may be related to a combination of the contiguity and strength of the ACC and the proximity of a cross‐shelf bathymetric low [ Klinck and Smith , 1993; Hofmann and Klinck , 1998; Rebesco et al , 1998; E. W. Domack, personal communication, 1999]. Modeling work suggests that offshore pressure gradients, similar to those created by northeastward ACC flow along the western Antarctic Peninsula, force upslope flow of UCDW within submarine canyon systems [ Klinck and Smith , 1993].…”

Section: Physical Settingmentioning

confidence: 99%

“…Although decadal‐ to millennial‐scale climate forcing mechanisms traditionally involve thermohaline reorganization initiated in the North Atlantic, atmospheric circulation changes have also been proposed to account for this variability [ Charles et al , 1996; Ninnemann et al , 1999]. One such hypothesis suggests that regional Southern Ocean ventilation changes may result from low‐ to high‐latitude atmospheric teleconnections involving Southern Hemisphere westerly wind field fluctuations [ Klinck and Smith , 1993; Charles et al , 1996; Labeyrie et al , 1996; Ninnemann et al , 1999]. While most proposed forcing mechanisms predict changes in Southern Ocean hydrography, existing Antarctic paleoclimate and paleoceanographic records have yet to provide a clear picture of decadal‐ to millennial‐scale Southern Ocean variability.…”

Section: Introductionmentioning

confidence: 99%

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Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

Shevenell

Kennett

2002

Paleoceanography

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The first moderate‐ to high‐resolution Holocene marine stable isotope record from the nearshore Antarctic continental shelf (Ocean Drilling Program (ODP) Hole 1098B) suggests sensitivity of the western Antarctic Peninsula hydrography to westerly wind strength and El Niño‐Southern Oscillation (ENSO)‐like climate variability. Despite proximity to corrosive Antarctic water masses, sufficient CaCO3 in Palmer Deep sediments exists to provide a high‐quality stable isotopic record (especially in the late Holocene). Coherence of benthic foraminifer δ18O, δ13C, sedimentologic, and CaCO3 fluctuations suggests that rapid (<20 years) Palmer Deep bottom water temperature fluctuations of 1°–1.5°C are associated with competitive interactions between two dominant oceanographic/climatic states. An abrupt shift from a warmer, stable Upper Circumpolar Deep Water (UCDW) state to a cooler, variable shelf water state occurred at ∼3.6 ka. Palmer Deep bottom waters oscillated between UCDW and shelf water‐dominated states between ∼3.6 and 0.05 ka. Cool shelf water intervals correlate with Neoglacial events, the most recent and largest being the Little Ice Age (LIA; ∼0.7–0.2 ka). Similarities between Palmer Deep and global Holocene records and the rapidity of inferred bottom water fluctuations suggest that western Antarctic Peninsula shelf hydrography has not been controlled by thermohaline reorganizations but by variable strength and/or position of the Southern Hemisphere westerly wind field. We suggest that these atmospheric perturbations may have originated in the low‐latitude tropical Pacific.

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Section: Physical Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

Shevenell

Kennett

2002

Paleoceanography

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“…The ACC in the Drake Passage is known to shift its location during the year (Hofmann and Whitworth, 1985) or possibly over longer time scales (Klinck and Smith, 1993). A shift of the SACCF north, even of only 10 km, leaves only a fraction of the large spawning area at the Antarctic Peninsula in the path of the SACCF, greatly reducing the possibility for transport of krill from the Antarctic Peninsula and the Weddell Sea to South Georgia.…”

Section: Key Processes Controlling Krill Transportmentioning

confidence: 99%

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part I: Circulation and particle tracking simulations

Fach

Klinck

2006

Deep Sea Research Part I: Oceanographic Research Papers

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The Harvard Ocean Prediction System (HOPS) is configured to simulate the circulation of the Scotia Sea and environs. This is part of a study designed to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia in the eastern Scotia Sea are sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. Comparison of the simulated circulation fields obtained from HOPS with observations showed good agreement. The surface circulation, particularly through the Drake Passage and across the Scotia Sea, matches observations, with its northeastward flow characterized by three high-speed fronts. Also, the Weddell Sea and the Brazil Current, and their associated transports match observations. In addition, mesoscale variability, an important component of the flow in this region, is found in the simulated circulation and the model is overall well suited to model krill transport. Drifter simulations conducted with HOPS showed that krill spawned in areas coinciding with known krill spawning sites along the west Antarctic Peninsula continental shelf can be entrained into the Southern Antarctic Circumpolar Current Front (SACCF). They are transported across the Scotia Sea to South Georgia in 10 months or less. Drifters originating on the continental shelf of the Weddell Sea can reach South Georgia as well; however, transport from this region averages about 20 months. Additional simulations show that such transport is sensitive to changes in wind stress and the location of the SACCF. The results of this study show that krill populations along the Antarctic Peninsula and the Weddell Sea are possible source populations that can provide krill to the South Georgia population. However, successful transport of krill to South Georgia is shown to depend on a multitude of factors, such as the location of the spawning area and timing of spawning, and variations in the location of the SACCF. Therefore, this study provides insight into which environmental factors control the successful transport of krill across the Scotia Sea and with it a better understanding of krill distribution in the region. r

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“…While the formation of NADW is related to northern hemispheric insolation and ice-sheet dynamics (Broecker and Denton, 1989;Berger and Wefer, 1996), the intensities of the Agulhas Current and the ACC depend on temperatures and the con¢g-urations of the major wind ¢elds in the southern hemisphere (Shannon et al, 1990;Klinck and Smith, 1993). Latest reconstructions from icecore data and marine proxy records from the southern hemisphere indicate changes in atmospheric CO 2 and variations in air and sea-surface temperatures to have preceded changes in global ice volume on short and long time scales (Charles et al, 1996;Little et al, 1997;Blunier et al, 1998;Brathauer and Abelmann, 1999;Vidal et al, 1999).…”

Section: Regional Conveyor Circulation In Response To Climate Variabimentioning

confidence: 99%

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

Kuhn

Diekmann

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

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During Leg 177 of the Ocean Drilling Program, an expanded sequence of Pliocene to Holocene calcareous muds was recovered at Site 1089 on a drift deposit in the southern Cape Basin (SE South Atlantic). The reconstruction of detrital sources and modes of sediment transport gives insight into the operational modes of regional current systems in response to climate variability over the last 590 kyr, as inferred from sedimentological and mineralogical parameters of the terrigenous sediment fraction. Terrigenous sediments mainly originate from African sources with minor contributions from distant southern sources (South America and Antarctica) and are supplied by circumpolar water masses, North Atlantic Deep Water (NADW), and surface currents of the Agulhas Current. Changes in clay mineralogy as tracers of deep and shallow ocean circulation, best displayed by variations in quartz/feldspar ratios and kaolinite/chlorite ratios of clay, reflect both the northward displacement of NADW injection into the Antarctic Circumpolar Current and a weakening of Agulhas Current leakage from the Indian Ocean around South Africa to the South Atlantic during glacial stages, sub-stages, and stadials. Modifications of these regional current patterns are consistent with perturbations in global conveyor circulation and climate variability on Milankovitch and subMilankovitch time scales. Elevated mass-accumulation rates of terrigenous matter generally document high particle fluxes and focusing effects by bottom-current action throughout the late Quaternary. Current sorting and coarsening of terrigenous mud, independently of its source signals, prevails during interglacial periods and is linked to a stronger flow of Antarctic Bottom Water and the invigoration of deep contour currents in response to long-term changes (100-kyr cyclicity) in Antarctic ice-sheet dynamics, high-amplitude fluctuations in global sea level, and increased bottomwater formation. ß

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Effect of wind changes during the Last Glacial Maximum on the circulation in the Southern Ocean

Cited by 33 publications

References 17 publications

Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part I: Circulation and particle tracking simulations

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

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