Eddy‐Driven Cross‐Shelf Transport in the East Australian Current Separation Zone

Malan, Neil; Archer, Matthew; Roughan, Moninya; Cetina‐Heredia, Paulina; Hemming, Michael; Rocha, Carlos; Schaeffer, Amandine; Suthers, Iain M.; Queiroz, Eduardo Vitarelli de

doi:10.1029/2019jc015613

Cited by 37 publications

(58 citation statements)

References 53 publications

(81 reference statements)

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“…The location of this low salinity plume is similar to the southernmost filament observed during a previous survey of the region (see Figure 12 in Piola et al, 2008) and also emerges in the numerical simulations reported by Matano et al (2014). Submesoscale instabilities facilitate the breakdown the relative vorticity barrier characteristics from WBC and allow cross-shore exchanges (Malan et al, 2020;Ribbe et al, 2018;Zhang & Gawarkiewicz, 2015).…”

Section: Journal Of Geophysical Research: Oceanssupporting

confidence: 84%

“…(2014). Submesoscale instabilities facilitate the breakdown the relative vorticity barrier characteristics from WBC and allow cross‐shore exchanges (Malan et al., 2020; Ribbe et al., 2018; Zhang & Gawarkiewicz, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…The strong current shear between both regions is a key dynamical element of the exchange. The relative vorticity barriers limit the exchange of water between the two regions (Franco et al., 2017; Malan et al., 2020; Roughan et al., 2011). However, shelf/ocean exchanges frequently occur where the WBC separate from the shelf break.…”

Section: Introductionmentioning

confidence: 99%

“…Cold, low salinity strips (also referred to as “Ford waters”) from the Middle Atlantic Bight over the Gulf Stream near Cape Hatteras (Ford et al., 1952) and low‐salinity filaments from Río de la Plata over the Brazil‐Malvinas Confluence (BMC Guerrero et al., 2014) are evidence of this process. In addition, submesoscale frontal instabilities (Arruda & da Silveira, 2019; Ismail & Ribbe, 2019; Malan et al., 2020; Ryan et al., 1999; Vélez‐Belchí et al., 2013) and wind stress (Bordin, 2018) can drive cross‐shore transport. In the southwest south Atlantic, for example, the Brazil Current separates from the shelf break near 37°S and energetic mesoscale instabilities promote an intense cross‐shelf exchange (Guerrero et al., 2014; Matano et al., 2014).…”

Section: Introductionmentioning

confidence: 99%

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Circulation and Hydrography in the Western South Atlantic Shelf and Export to the Deep Adjacent Ocean: 30°S to 40°S

et al. 2020

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High sea surface chlorophyll concentration on the Argentine Continental Shelf frequently extends to the deep ocean in the vicinity of the Brazil/Malvinas Confluence (BMC). The offshore transport of shelf waters likely plays a key role in the biogeochemical balance of the western South Atlantic and promotes the offshore transport of planktonic species. We analyze data from an oceanographic survey carried out in the western South Atlantic shelf between 31°S and 38°S in October 2013. We describe the distribution and circulation of the water masses and focus on the exchanges with the open ocean. On-shelf subsurface intrusions of oceanic waters and river discharge supply nutrients to the shelf. A low-salinity tongue of Río de la Plata (RDP) waters extends northward to 32°S. Below these waters Subantarctic and Subtropical Shelf Waters (SASW and STSW) meet to form the Subtropical Shelf Front. The main SASW branch, oversaturated in oxygen and with high-fluorescence mixes with a detachment of Brazil Current waters at 38°S and is exported offshore along the BMC. A second branch of SASW reaches 33°S mixing along its way with RDP and STSW and returns southward after splitting into an onshore and an offshore branch. The offshore branch is exported to the open ocean through the BMC. These export routes are in overall qualitative agreement with those indicated by a high-resolution reanalysis. We estimate a net off-shelf transport (geostrophic [96.2%] plus Ekman [3.8%]) of 3.44 Sv to the open ocean between 32.1°S and 37.7°S. The majority of the offshore flow occurs between 34.7°S and 37.7°S.

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Section: Journal Of Geophysical Research: Oceanssupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Circulation and Hydrography in the Western South Atlantic Shelf and Export to the Deep Adjacent Ocean: 30°S to 40°S

et al. 2020

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“…This study has helped identifying mesoscale eddies offshore from Fraser Island, which have rarely been explored in previous studies. Past studies examined eddies off the northeast coast of Australia formed by the EAC separation (O'Kane et al, 2011;Suthers et al, 2011;Roughan et al, 2017;Oke et al, 2019;Malan et al, 2020), mostly between 30 • S and 34 • S, giving rise to the Tasman Front (Suthers et al, 2011;Cetina-Heredia et al, 2014). Little attention has been devoted to details of eddies north of the separation points-especially the eddy pair phenomena, which occur frequently.…”

Section: Resultsmentioning

confidence: 99%

A Study on an Anticyclonic-Cyclonic Eddy Pair Off Fraser Island, Australia

Wang

et al. 2020

Front. Mar. Sci.

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This research examines a cyclonic-anticyclonic eddy (AE) pair off Fraser Island next to the eastern Australian coast in 2009 using the Bluelink Reanalysis data, where the local eddies are poorly understood. This eddy pair formed in July and dissipated in November. We detailed the horizontal and vertical structures of the eddy pair in terms of three-dimensional variations in relative vorticity, hydrographic properties, velocity, and dynamic structures, which presented notable scales of the eddy pair. The AE formed beside the meandering of the East Australian Current (EAC) at 24°S and had a tilting structure in the upper 1,000 m toward the EAC. A cyclonic eddy (CE) formed a month later and interacted with the AE, which had a tilting structure toward the AE in the upper 1,000 m. Heterogeneity in the AE and CE composing this eddy pair was observed in the horizontal and vertical planes. The AE had a stronger and more coherent dynamic structure than the CE. The AE and the EAC interacted in the generation stage when the EAC path shifted eastward, away from the coast. As the EAC subsequently swung back to the coastal area, the AE and the EAC separated. The AE then interacted with the surrounding eddy fields, propagated westward, before finally merging again with the EAC. The energy transfer during this process also indicated the interactions among the eddy pair, the surrounding eddy fields and the EAC. Baroclinic instability (BCI) was a main contributor to the AE in the generation stage. Barotropic instability (BTI) also contributed energy to the AE when it interacted with the EAC but accounted for a much smaller proportion. Both BCI and BTI contributed to the CE for most of its life cycle but to a much less extend than to the AE. The zonal heat and salt mass transported by the AE and CE were calculated based on a Lagrangian framework method, and these amounts were considerable compared with global zonal averaged heat and salt mass transported by other mesoscale eddies.

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Population connectivity across east Australia's bioregions and larval duration of the range‐extending sea star Meridiastra calcar

Klanten,

Gall,

Barbosa

et al. 2023

Aquatic Conservation

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The diversity and distribution of marine species in eastern Australia is influenced by one of the world's strongest western boundary currents, the East Australia Current, which propels water and propagules poleward, a flow intensifying due to climate change. Population genetic structure of the asterinid sea star Meridiastra calcar was investigated across its range in eastern Australia (12° of latitude, 2,500 km) from northern New South Wales to its poleward‐extending range in Tasmania at the southern edge influence of the East Australia Current. Population structure and connectivity of M. calcar were examined across six bioregions using six microsatellite loci (nuclear DNA) and the control region (mitochondrial DNA). The potential influence of the extent of M. calcar's intertidal rock platform habitat was also assessed. Genetic structure analysis indicated that the Hawkesbury Shelf contained distinct genetic clusters, whereas the two sites in the Batemans Shelf differed from each other, with Jervis Bay Marine Park having just one genetic cluster. The Manning Shelf, Twofold Shelf, and Bruny bioregions all had similar genetic composition. Strong self‐seeding (68–98%) was indicated by microsatellite loci for all bioregions, with lower (0.3–6.5%) migration between bioregions. Poleward (New South Wales to Tasmania) migration was low except from the Manning Shelf (30%). Contemporary population connectivity and genetic structure of M. calcar appear to be influenced by ocean currents, habitat distribution, and its short planktonic larval duration, which was a minimum of 12–14 days, depending on availability of a settlement cue. The dominance of unique genetic groups in the Hawkesbury bioregion shows the importance of this region for M. calcar and possibly a diversity of co‐distributed rock platform species. This highlights how important it is to have a large marine park in the Hawkesbury bioregion, which is presently lacking.

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Eddy‐Driven Cross‐Shelf Transport in the East Australian Current Separation Zone

Cited by 37 publications

References 53 publications

Circulation and Hydrography in the Western South Atlantic Shelf and Export to the Deep Adjacent Ocean: 30°S to 40°S

Circulation and Hydrography in the Western South Atlantic Shelf and Export to the Deep Adjacent Ocean: 30°S to 40°S

A Study on an Anticyclonic-Cyclonic Eddy Pair Off Fraser Island, Australia

Population connectivity across east Australia's bioregions and larval duration of the range‐extending sea star Meridiastra calcar

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