Characteristics of warm rings in the African sector of the Antarctic Circumpolar Current

Gouretski, Victor V.; Danilov, A. I.

doi:10.1016/0967-0637(94)90037-x

Cited by 31 publications

(19 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This process, however, occurs on much longer time scales than those important for plankton dynamics. As sharp meridional gradients of temperature and salinity are found down to the bottom, the APF has a pronounced expression throughout the water column (Gouretski and Danilov, 1994). The strong horizontal density gradient leads to baroclinic instability which in some regions is triggered by local bottom topography (Chelton et al, 1990;Veth et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…These eddies have a diameter of roughly 80 km which corresponds to the spatial decorrelation scale of 85 km derived from Geosat altimeter data for the ACC (Gille and Kelly, 1996). Observed diameters of eddies or rings in the ACC generally cover a wide range from 60 to 250 km (Bryden, 1983;Nowlin and Klinck, 1986;Gouretski and Danilov, 1994).…”

Section: Hydrography and Frontal Dynamicsmentioning

confidence: 99%

“…As a consequence, meandering currents establish and isolated eddies are formed. Warm or cold core eddies (or rings) on either side of the front are frequently observed (Ikeda et al, 1989;Gouretski and Danilov, 1994). Eddies are often assumed to promote phytoplankton growth as they contribute to cross frontal and vertical nutrient exchange (e.g.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Regional ecosystem dynamics in the ACC: simulations with a three-dimensional ocean-plankton model

Hense

Timmermann

Beckmann

et al. 2003

Journal of Marine Systems

View full text Add to dashboard Cite

Within the high nutrient -low chlorophyll regime of the Antarctic Circumpolar Current (ACC), high phytoplankton concentrations are frequently observed in the vicinity of the Antarctic Polar Front (APF). As is typical for frontal systems, hydrography in this region is characterized by meanders and eddies as well as up-and downwelling cells which redistribute nutrients and influence the depth of the euphotic zone.To study the processes leading to the observed phytoplankton distribution, a coupled ocean-plankton model for ecosystem studies in the ACC has been developed. The ocean component is an eddy-resolving version of the s-Coordinate Primitive Equation Model (SPEM). The model has a horizontal resolution of 1/12j and a vertical resolution increased near the surface. The biological model (BIMAP) comprises two biogeochemical cycles-silica and nitrogen-and a prognostic iron compartment to include possible effects of micronutrient limitation.Model results indicate that part of the ecosystem's regional variability can be attributed to the effect of vertical and horizontal advection. However, frontal dynamics alone cannot explain the observed enhanced concentrations of phytoplankton biomass near the APF and the minima in the northern and southern ACC. Only when iron limitation is taken into account, the model simulates plankton concentrations in close agreement with observations during the SO-JGOFS cruises. While in the northern ACC phytoplankton growth is limited by silicate, primary production is limited by iron south of the APF. Near the APF, mesoscale iron upwelling enhances primary production, leading to increased phyto-and zooplankton biomass. The meridional structure with two plankton maxima is closely linked to the cross-front overturning circulation. This double-cell circulation with two upwelling branches is caused by the northward sloping large-scale bottom topography. D

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Hydrography and Frontal Dynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Regional ecosystem dynamics in the ACC: simulations with a three-dimensional ocean-plankton model

Hense

Timmermann

Beckmann

et al. 2003

Journal of Marine Systems

View full text Add to dashboard Cite

show abstract

“…Drake Passage is where the PF develops its largest meridional excursion, leading to increased baroclinic instability and a large surface of exchange across the front, two conditions that favor increased eddy contribution. At the Southwest Indian Ridge, observational studies have reported the presence of a warm eddy corridor that allows some eddies to cross the PF and transport heat to the Antarctic zone (e.g., Gouretski and Danilov 1994;Ansorge et al 2014).…”

Section: Transportmentioning

confidence: 99%

Role of Mesoscale Eddies in Cross-Frontal Transport of Heat and Biogeochemical Tracers in the Southern Ocean

Dufour

Griffies

Souza

et al. 2015

Journal of Physical Oceanography

122

136

View full text Add to dashboard Cite

This study examines the role of processes transporting tracers across the Polar Front (PF) in the depth interval between the surface and major topographic sills, which this study refers to as the ''PF core.'' A preindustrial control simulation of an eddying climate model coupled to a biogeochemical model [GFDL Climate Model, version 2.6 (CM2.6)-simplified version of the Biogeochemistry with Light Iron Nutrients and Gas (miniBLING) 0.18 ocean model] is used to investigate the transport of heat, carbon, oxygen, and phosphate across the PF core, with a particular focus on the role of mesoscale eddies. The authors find that the total transport across the PF core results from a ubiquitous Ekman transport that drives the upwelled tracers to the north and a localized opposing eddy transport that induces tracer leakages to the south at major topographic obstacles. In the Ekman layer, the southward eddy transport only partially compensates the northward Ekman transport, while below the Ekman layer, the southward eddy transport dominates the total transport but remains much smaller in magnitude than the near-surface northward transport. Most of the southward branch of the total transport is achieved below the PF core, mainly through geostrophic currents. This study finds that the eddy-diffusive transport reinforces the southward eddy-advective transport for carbon and heat, and opposes it for oxygen and phosphate. Eddy-advective transport is likely to be the leading-order component of eddy-induced transport for all four tracers. However, eddy-diffusive transport may provide a significant contribution to the southward eddy heat transport due to strong along-isopycnal temperature gradients.

show abstract

“…1), and to make this data set available to the scientific community. The interaction of the Antarctic Circumpolar Current with the shallow topographic features of the Southwest Indian Ocean Ridge plays an important role in the generation of open-ocean eddies just south of the polar front (Gouretski and Danilov, 1994;Pollard and Read, 2001;Durgadoo et al, 2011;Ansorge et al, 2015). The subsequent movement of these eddies in a southerly direction, into the Southern Ocean proper, represents an ideal natural laboratory for the in situ observation and study of the eddy transport of heat, salt and chemicals across strong frontal zones in the Southern Ocean.…”

Section: Introductionmentioning

confidence: 99%

In situ measurement of the biogeochemical properties of Southern Ocean mesoscale eddies in the Southwest Indian Ocean, April 2014

Villiers

Siswana

Vena

2015

Earth Syst. Sci. Data

View full text Add to dashboard Cite

Abstract. Several open-ocean mesoscale features -a "young" warm-core (anti-cyclonic) eddy at 52 • S, an "older" warm-core eddy at 57.5 • S and an adjacent cold-core (cyclonic) eddy at 56 • S -were surveyed during a R/V S.A. Agulhas II cruise in April 2014. The main aim of the survey was to obtain hydrographical and biogeochemical profile data for contrasting open-ocean eddies in the Southern Ocean, which will be suitable for comparative study and modelling of their heat, salt and nutrient characteristics, and the changes that occur in these properties as warm-core eddies migrate from the polar front southwards. The major result is that the older warm-core eddy at 57.5 • S is, at its core, 2.7 • C colder than a younger eddy at 52 • S, while its dissolved silicate levels are almost 500 % higher and accompanied by chlorophyll a levels that are more than 200 % higher than that in the younger eddy. A total of 18 CTD stations were occupied in a sector south of the Southwest Indian Ridge, along three transects crossing several mesoscale features identified from satellite altimetry data prior to the cruise. The CTD data, as well as chlorophyll a and dissolved nutrient data (for NO

show abstract

Characteristics of warm rings in the African sector of the Antarctic Circumpolar Current

Cited by 31 publications

References 30 publications

Regional ecosystem dynamics in the ACC: simulations with a three-dimensional ocean-plankton model

Regional ecosystem dynamics in the ACC: simulations with a three-dimensional ocean-plankton model

Role of Mesoscale Eddies in Cross-Frontal Transport of Heat and Biogeochemical Tracers in the Southern Ocean

In situ measurement of the biogeochemical properties of Southern Ocean mesoscale eddies in the Southwest Indian Ocean, April 2014

Contact Info

Product

Resources

About