Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring

Zhang, Weifeng G.; Partida, Jacob

doi:10.1029/2018jc013794

Cited by 19 publications

(15 citation statements)

References 44 publications

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“…The role of the NESC can now be quantified in targeted modeling experiments to reproduce the results of this observational study. The impact of WCRs in recent years on the observed shelf slope water warming can be studied dynamically as in Zhang and Partida (2018) (and references therein) using this data set. Studies such as Myers and Drinkwater (1989) can be revisited to understand the impact of the larger number of WCRs (after the regime shift in 2000) on the various groundfish populations in the GOM and GB area.…”

Section: Discussionmentioning

confidence: 99%

A Census of the Warm‐Core Rings of the Gulf Stream: 1980–2017

et al. 2020

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A census of Gulf Stream (GS) warm‐core rings (WCRs) is presented based on 38 years (1980–2017) of data. The census documents formation and demise times and locations, and formation size for all 961 WCRs formed in the study period that live for a week or more. A clear regime shift was observed around the Year 2000 and was reported by a subset of authors (Gangopadhyay et al., 2019, https://doi.org/10.1038/s41598-019-48661-9). The WCR formation over the whole region (75–55°W) increased from an average of 18 per year during Regime 1 (1980–1999) to 33 per year during Regime 2 (2000–2017). For geographic analysis formation locations were grouped in four 5° zones between 75°W and 55°W. Seasonally, WCR formations show a significant summer maxima and winter minima, a pattern that is consistent through all zones and both temporal regimes. The lifespan and size distribution show progressively more rings with higher longevity and greater size when formed to the east of 70°W. The average lifespan of the WCRs in all four zones decreased by 20–40% depending on zones and/or seasons from Regime 1 to Regime 2, while the size distribution remained unchanged across regimes. The ring footprint index, a first‐order signature of impact of the WCRs on the slope, increased significantly (26–90%) for all zones from Regime 1 to Regime 2, with the highest percent increase in Zone 2 (70–65°W). This observational study establishes critical statistical and dynamical benchmarks for validating numerical models and highlights the need for further dynamical understanding of the GS‐ring formation processes.

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Section: Discussionmentioning

confidence: 99%

A Census of the Warm‐Core Rings of the Gulf Stream: 1980–2017

et al. 2020

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“…Open ocean environments are much more complex and subject to the influences of different flows, including mesoscale, sub-mesoscale, tidal, upwelling, and downwelling currents. In the Slope Water off the Northeast U.S. coast where this study occurred, flow can be impacted by the Gulf Stream, warm-core rings, subduction and upwelling along the ring periphery, slope current, tides, and internal tides (Joyce, 1984;Flagg et al, 2006;Kelly et al, 2016;Zhang and Partida, 2018). These flows could redistribute eDNA in the three-dimensional space.…”

Section: Interpreting Mesopelagic Edna Signalsmentioning

confidence: 98%

Exploring the Use of Environmental DNA (eDNA) to Detect Animal Taxa in the Mesopelagic Zone

et al. 2021

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Animal biodiversity in the ocean’s vast mesopelagic zone is relatively poorly studied due to technological and logistical challenges. Environmental DNA (eDNA) analyses show great promise for efficiently characterizing biodiversity and could provide new insight into the presence of mesopelagic species, including those that are missed by traditional net sampling. Here, we explore the utility of eDNA for identifying animal taxa. We describe the results from an August 2018 cruise in Slope Water off the northeast United States. Samples for eDNA analysis were collected using Niskin bottles during five CTD casts. Sampling depths along each cast were selected based on the presence of biomass as indicated by the shipboard Simrad EK60 echosounder. Metabarcoding of the 18S V9 gene region was used to assess taxonomic diversity. eDNA metabarcoding results were compared with those from net-collected (MOCNESS) plankton samples. We found that the MOCNESS sampling recovered more animal taxa, but the number of taxa detected per liter of water sampled was significantly higher in the eDNA samples. eDNA was especially useful for detecting delicate gelatinous animals which are undersampled by nets. We also detected eDNA changes in community composition with depth, but not with sample collection time (day vs. night). We provide recommendations for applying eDNA-based methods in the mesopelagic including the need for studies enabling interpretation of eDNA signals and improvement of barcode reference databases.

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“…1a) has been shown to flow northward into the Tasman Sea and move along the shelf for up to 200 km (BR12), during which time there are many opportunities for it to interact with anticyclonic eddies shed from the EAC. Shelf-deep ocean interaction of this type has been documented in the Mid-Atlantic Bight; Gulf Stream anticyclonic eddies come into contact with shelf water, which instigates frontogenesis and subduction (Zhang and Partida 2018). The submesoscale lenses observed by BR12 had water properties matching Bass Strait.…”

Section: B Submesoscale Lenses Of Anomalous Water In the Tasman Seamentioning

confidence: 99%

Observations of Submesoscale Variability and Frontal Subduction within the Mesoscale Eddy Field of the Tasman Sea

Archer

Schaeffer

Keating

et al. 2020

Journal of Physical Oceanography

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Submesoscale lenses of water with anomalous hydrographic properties have previously been observed in the East Australian Current (EAC) system, embedded within the thermocline of mesoscale anticyclonic eddies. The waters within these lenses have high oxygen content and temperature–salinity properties that signify a surface origin. However, it is not known how these lenses form. This study presents field observations that provide insight into a possible generation mechanism via subduction at upper-ocean fronts. High-resolution hydrographic and velocity measurements of submesoscale activity were taken across a front between a mesoscale eddy dipole downstream of the EAC separation point. The front had O(1) Rossby number, strong vertical shear, and flow conducive to symmetric instability. Frontogenesis was measured in conjunction with subduction of an anticyclonic water parcel, indicative of intrathermocline eddy formation. Twenty-five years of satellite imagery reveals the existence of strong mesoscale strain coupled with strong temperature fronts in this region and indicates the conditions that led to frontal subduction observed here are a persistent feature. These processes impact the vertical export of tracers from the surface and dissipation of mesoscale kinetic energy, implicating their importance for understanding regional ocean circulation and biological productivity.

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Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring

Cited by 19 publications

References 44 publications

A Census of the Warm‐Core Rings of the Gulf Stream: 1980–2017

A Census of the Warm‐Core Rings of the Gulf Stream: 1980–2017

Exploring the Use of Environmental DNA (eDNA) to Detect Animal Taxa in the Mesopelagic Zone

Observations of Submesoscale Variability and Frontal Subduction within the Mesoscale Eddy Field of the Tasman Sea

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