An additional deep-water mass in Drake Passage as revealed by 3He data

Well, Roland; Roether, Wolfgang; Stevens, David P.

doi:10.1016/s0967-0637(03)00050-5

Cited by 54 publications

(54 citation statements)

References 35 publications

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“…2b). Close to the Patagonian shelf (55-56.5 • S), between ∼ 2000-3000 m depth Southeast Pacific Deep Slope Water (SPDSW) is present with elevated δ 3 He (Well et al, 2003;Sudre et al, 2011) and DMn (Middag et al, 2012), related to hydrothermal activity in the South Pacific source region of this water mass. The Drake Passage is known for the occurrence of mesoscale eddies.…”

Section: Hydrographymentioning

confidence: 99%

“…The deep Drake Passage is dominated by circumpolar deep waters which contain generally ∼ 0.4-0.5 nM DFe (Klunder et al, 2011a). However, at ∼ 2000 m depth at the Patagonian continental shelf, an additional water mass derived from the East Pacific Ocean, carrying properties of hydrothermal origin (Well et al, 2003;Sudre et al, 2011) was observed, which forms a potential source of DFe to the deep Drake Passage.…”

Section: Introductionmentioning

confidence: 99%

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Dissolved Fe across the Weddell Sea and Drake Passage: impact of DFe on nutrient uptake

et al. 2014

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Abstract. This manuscript reports the first full depth distributions of dissolved iron (DFe) over a high-resolution Weddell Sea and Drake Passage transect. Very low dissolved DFe concentrations (0.01–0.1 nM range) were observed in the surface waters of the Weddell Sea, and within the Drake Passage polar regime. Locally, enrichment in surface DFe was observed, likely due to recent ice melt (Weddell Sea) or dust deposition (Drake Passage). As expected, in low DFe regions, usually a small silicate drawdown compared to the nitrate drawdown was observed. However, the difference in drawdown between these nutrients appeared not related to DFe availability in the western Weddell Sea. In this region with relatively small diatoms, no relationship between N : P and N : Si removal ratios and DFe was observed. In comparison, along the Greenwich Meridian (Klunder et al., 2011a), where diatoms are significantly larger, the N : P and N : Si removal ratios did increase with increasing DFe. These findings confirm the important role of DFe in biologically mediated nutrient cycles in the Southern Ocean and imply DFe availability might play a role in shaping phytoplankton communities and constraining cell sizes. Over the shelf around the Antarctic Peninsula, higher DFe concentrations (>1.5 nM) were observed. These elevated concentrations of Fe were transported into Drake Passage along isopycnal surfaces. Near the South American continent, high (>2 nM) DFe concentrations were caused by fluvial/glacial input of DFe. On the Weddell Sea side of the Peninsula region, formation of deep water (by downslope convection) caused relatively high Fe (0.6–0.8 nM) concentrations in the bottom waters relative to the water masses at mid-depth (0.2–0.4 nM). During transit of Weddell Sea Bottom Water to the Drake Passage, through the Scotia Sea, additional DFe is taken up from seafloor sources, resulting in highest bottom water concentrations in the southernmost part of the Drake Passage in excess of 1 nM. The Weddell Sea Deep Water concentrations (∼0.32 nM) were consistent with the lowest DFe concentrations observed in Antarctic bottom water in the Atlantic Ocean.

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Section: Hydrographymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dissolved Fe across the Weddell Sea and Drake Passage: impact of DFe on nutrient uptake

et al. 2014

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“…Yet estimates of the rates of these processes and of the upwelling that they induce are poorly constrained by observations. Here we take advantage of a natural tracer-release experiment-an injection of mantle helium from hydrothermal vents into the Circumpolar Current near Drake Passage 9 -to measure the rates of mixing and upwelling in the current's intermediate layers over a sector that spans nearly onetenth of its circumpolar path. Dispersion of the tracer reveals rapid upwelling along density surfaces and intense mixing across density surfaces, both occurring at rates that are an order of magnitude greater than rates implicit in models of the average Southern Ocean overturning [4][5][6][7][8] .…”

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confidence: 99%

Short-circuiting of the overturning circulation in the Antarctic Circumpolar Current

Garabato

Stevens

Watson

et al. 2007

Nature

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The oceanic overturning circulation has a central role in the Earth's climate system and in biogeochemical cycling, as it transports heat, carbon and nutrients around the globe and regulates their storage in the deep ocean. Mixing processes in the Antarctic Circumpolar Current are key to this circulation, because they control the rate at which water sinking at high latitudes returns to the surface in the Southern Ocean. Yet estimates of the rates of these processes and of the upwelling that they induce are poorly constrained by observations. Here we take advantage of a natural tracer-release experiment - an injection of mantle helium from hydrothermal vents into the Circumpolar Current near Drake Passage - to measure the rates of mixing and upwelling in the current's intermediate layers over a sector that spans nearly one-tenth of its circumpolar path. Dispersion of the tracer reveals rapid upwelling along density surfaces and intense mixing across density surfaces, both occurring at rates that are an order of magnitude greater than rates implicit in models of the average Southern Ocean overturning. These findings support the view that deep-water pathways along and across density surfaces intensify and intertwine as the Antarctic Circumpolar Current flows over complex ocean-floor topography, giving rise to a short circuit of the overturning circulation in these regions

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“…Along the southernmost Chile margin, the southward flowing Cape Horn Current (CHC), a northern branch of the ACC that continues toward the Drake Passage, provides a major fraction of the present-day northern Drake Passage transport (Well et al, 2003). Satellite-tracked surface drifters reveal that after crossing the East Pacific Rise (EPR), Subantarctic surface water of the ACC is transported northeastward across the Southeast Pacific toward the Chilean coast at ~45°S/75°W (Chaigneau and Pizarro, 2005).…”

Section: Oceanographic Settingmentioning

confidence: 99%

“…The water depths covered by the planned sites sample the major water masses of the northern ACC from AAIW, across CDW/PDW, and potentially down to AABW ( Figure F13). The sites are located underneath the southward-flowing CHC (Figure F2), a northern branch of the ACC that continues toward the Drake Passage and provides a major fraction of the present-day northern Drake Passage transport (Well et al, 2003).…”

Section: Proposed Drill Sitesmentioning

confidence: 99%

Expedition 383 Prospectus: Dynamics of the Pacific Antarctic Circumpolar Current (DYNAPACC)

Lamy¹,

Winckler²,

Zarikian³

2018

International Ocean Discovery Program Scientific Prospectus

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An additional deep-water mass in Drake Passage as revealed by 3He data

Abstract: We present 3

Cited by 54 publications

References 35 publications

Dissolved Fe across the Weddell Sea and Drake Passage: impact of DFe on nutrient uptake

Dissolved Fe across the Weddell Sea and Drake Passage: impact of DFe on nutrient uptake

Short-circuiting of the overturning circulation in the Antarctic Circumpolar Current

Expedition 383 Prospectus: Dynamics of the Pacific Antarctic Circumpolar Current (DYNAPACC)

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