Chlorophyll blooms in the Antarctic Zone south of Australia and New Zealand in reference to the Antarctic Circumpolar Current fronts and sea ice forcing

Abstract The Antarctic Circumpolar Current (ACC) plays a crucial role in global ocean circulation by fostering deep-water upwelling and formation of new water masses. On geological time-scales, ACC variations are poorly constrained beyond the last glacial. Here, we reconstruct changes in ACC strength in the central Drake Passage over the past 140,000 years, based on grain-size and geochemical characteristics. We found significant glacial-interglacial changes of ACC flow speed, with reduced ACC intensity during glacials and a more vigorous circulation in interglacials. Superimposed on these orbital-scale changes are high-amplitude millennial-scale fluctuations, with ACC strength maxima correlating with diatom-based Antarctic winter sea-ice minima, particularly during full glacial conditions. We hypothesize that the ACC is closely linked to Southern Hemisphere millennial-scale climate oscillations, amplified through Antarctic sea ice extent changes. These strong ACC variations regulated Pacific-Atlantic water exchange via the “cold water route” and affected the Atlantic Meridional Overturning Circulation and marine carbon storage.

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ENSO and variability of the Antarctic Peninsula pelagic marine ecosystem

Antarctic Science ◽

10.1017/s0954102008001636 ◽

2008 ◽

Vol 21 (2) ◽

pp. 135-148 ◽

Cited By ~ 62

Author(s):

Valerie J. Loeb ◽

Eileen E. Hofmann ◽

John M. Klinck ◽

Osmund Holm-Hansen ◽

Warren B. White

Keyword(s):

Sea Ice ◽

Antarctic Peninsula ◽

Antarctic Circumpolar Current ◽

Southern Oscillation ◽

Marine Ecosystem ◽

Weddell Sea ◽

Enso Variability ◽

Decadal Scale ◽

Circumpolar Current ◽

The Antarctic

AbstractThe West Antarctic Peninsula region is an important source of Antarctic krill (Euphausia superba) in the Southern Ocean. From 1980–2004 abundance and concentration of phytoplankton and zooplankton, krill reproductive and recruitment success and seasonal sea ice extent here were significantly correlated with the atmospheric Southern Oscillation Index and exhibited three- to five-year frequencies characteristic of El Niño–Southern Oscillation (ENSO) variability. This linkage was associated with movements of the Southern Antarctic Circumpolar Current Front and Boundary, a changing influence of Antarctic Circumpolar Current and Weddell Sea waters, and eastward versus westward flow and mixing processes that are consistent with forcing by the Antarctic Dipole high-latitude climate mode. Identification of hydrographic processes underlying ecosystem variability presented here were derived primarily from multi-disciplinary data collected during 1990–2004, a period with relatively stable year-to-year sea ice conditions. These results differ from the overwhelming importance of seasonal sea ice development previously established using 1980–1996 data, a period marked by a major decrease in sea ice from the Antarctic Peninsula region in the late 1980s. These newer results reveal the more subtle consequences of ENSO variability on biological responses. They highlight the necessity of internally consistent long-term multidisciplinary datasets for understanding ecosystem variability and ultimately for establishing well-founded ecosystem management. Furthermore, natural environmental variability associated with interannual- and decadal-scale changes in ENSO forcing must be considered when assessing impacts of climate warming in the Antarctic Peninsula–Weddell Sea region.

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Multi-scale factors influencing seabird assemblages in the African sector of the Southern Ocean

Antarctic Science ◽

10.1017/s0954102013000138 ◽

2013 ◽

Vol 26 (1) ◽

pp. 38-48 ◽

Cited By ~ 7

Author(s):

Morgan L. Commins ◽

Isabelle Ansorge ◽

Peter G. Ryan

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Antarctic Circumpolar Current ◽

Polar Front ◽

Latitudinal Gradients ◽

Antarctic Polar Front ◽

Sea Ice Extent ◽

Southern Boundary ◽

Circumpolar Current ◽

The Antarctic

AbstractOceanic fronts are important foraging areas for many top predators, but they also define biogeographical boundaries to animals in the Southern Ocean and play a role in structuring seabird assemblages. Understanding the factors driving patterns in the spatial and temporal distribution of seabirds is important to infer the likely impact of a changing climate. Latitudinal transects south of Africa in two summers indicate that fronts and sea ice extent play key roles in determining seabird assemblages. We observed 37 seabird taxa and found five seabird assemblages. The Subtropical Convergence and pack ice-edge form the strongest biogeographical boundaries, whereas the Sub-Antarctic Front and Antarctic Polar Front are less well defined. As summer progresses, the Southern Antarctic Circumpolar Current Front (the Antarctic Divergence or southern boundary of the Antarctic Circumpolar Current) becomes important, when a distinct seabird assemblage forms north of the retreating sea ice following an influx of great shearwatersPuffinus gravis(O'Reilly), blue petrelsHalobaena caerulea(Gmelin), Kerguelen petrelsLugensa brevirostris(Lesson) and southern fulmarsFulmarus glacialoides(Smith). Seabird assemblages show strong seasonality and are predictable between years. They are structured primarily by latitudinal gradients and secondarily by seasonal variation in sea-surface temperature and ice cover within their latitudinal habitat zones.

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Thermal isolation of Campbell Plateau, New Zealand, by the Antarctic Circumpolar Current over the past 130 kyr

Paleoceanography ◽

10.1029/2003pa000975 ◽

2004 ◽

Vol 19 (4) ◽

pp. n/a-n/a ◽

Cited By ~ 53

Author(s):

Helen L. Neil ◽

Lionel Carter ◽

Michele Y. Morris

Keyword(s):

New Zealand ◽

Antarctic Circumpolar Current ◽

Thermal Isolation ◽

The Past ◽

Circumpolar Current ◽

The Antarctic

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Nonlinear Differential Equations Modeling the Antarctic Circumpolar Current

Journal of Mathematical Fluid Mechanics ◽

10.1007/s00021-021-00618-7 ◽

2021 ◽

Vol 23 (4) ◽

Author(s):

Jifeng Chu ◽

Kateryna Marynets

Keyword(s):

Fixed Point ◽

Differential Equations ◽

Boundary Conditions ◽

Topological Degree ◽

Antarctic Circumpolar Current ◽

Fixed Point Theorems ◽

Nonlinear Differential Equations ◽

Existence Results ◽

Circumpolar Current ◽

The Antarctic

AbstractThe aim of this paper is to study one class of nonlinear differential equations, which model the Antarctic circumpolar current. We prove the existence results for such equations related to the geophysical relevant boundary conditions. First, based on the weighted eigenvalues and the theory of topological degree, we study the semilinear case. Secondly, the existence results for the sublinear and superlinear cases are proved by fixed point theorems.

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