Compact, intrathermocline eddies in the Sargasso Sea

Dugan, John P.; Mied, Richard P.; Mignerey, Peter C.; Schuetz, A.

doi:10.1029/jc087ic01p00385

Cited by 63 publications

(35 citation statements)

References 9 publications

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“…This three‐dimensional spatial structure of temperature, specific conductance and density is typical for oceanic anticyclonic lens‐like eddies (Dugan et al ; Armi and Zenk ; McWilliams ; Kostianoy and Belkin ). Eddies in ice‐covered lakes have been observed previously.…”

Section: Hydrological Structure Beneath the Ice Ringsmentioning

confidence: 82%

Giant ice rings on lakes Baikal and Hovsgol: Inventory, associated water structure and potential formation mechanism

Kouraev

Zakharova

Rémy

et al. 2016

Limnology & Oceanography

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Observations of giant ice rings on Lake Baikal (Russia) have recently sparked scientific and public interest. However, there is still no clear consensus on their origins. Here, we provide an inventory of the ice rings based on satellite imagery and photography for 1974-2014. We have identified 45 rings on Lake Baikal (compared with 13 previously known) and also for the first time four rings for the neighbouring Lake Hovsgol (Mongolia). The results of our hydrographic surveys beneath the ice rings in Lake Baikal in 2012-2014 and in Lake Hovsgol in 2015 show the presence of warm double-convex lens-like eddies before and during manifestation of ice rings. We suggest that these eddies are the driving factor for the formation of ice rings in these lakes. We reassess the existing hypotheses of ice ring formation and discuss the potential mechanisms of eddy formation.

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Section: Hydrological Structure Beneath the Ice Ringsmentioning

confidence: 82%

Giant ice rings on lakes Baikal and Hovsgol: Inventory, associated water structure and potential formation mechanism

Kouraev

Zakharova

Rémy

et al. 2016

Limnology & Oceanography

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“…Thus, TIVs contain a range of flow features normally associated with midlatitude submesoscale physics, such as strong fronts, vertical velocities, ageostrophic flows, and frontogenesis (Marchesiello et al 2011;Ubelmann and Fu 2011). In particular, they share features in common with submesoscale coherent vortices and intrathermocline eddies (ITEs), that is, lenticular coherent anticyclonic vortices that are found in the thermocline and that are characterized by water in their cores that has anomalously low PV (Dugan et al 1982;McWilliams 1985;Kostianoy and Belkin 1989).…”

Section: Introductionmentioning

confidence: 99%

Potential Vorticity Dynamics of Tropical Instability Vortices

Holmes

Thomas

Thompson

et al. 2014

Journal of Physical Oceanography

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Tropical instability vortices (TIVs) in the equatorial Pacific exhibit energetic horizontal and vertical circulation characterized by regions of high Rossby number and low Richardson number. Their strong anticyclonic vorticity and vertical shear can influence the broader-scale circulation by driving lateral mixing and vertical exchange between the ocean surface and interior. The authors use a set of nested high-resolution simulations of the equatorial Pacific, with a finest grid size of 3 km, to examine the vortex dynamics associated with TIV core water formation. TIV cores are characterized by low values of the Ertel potential vorticity (PV) as the relative vorticity is anticyclonic with magnitude comparable to the local Coriolis parameter. A study of the variation of PV and other scalars along Lagrangian fluid parcel tracks entering the TIVs shows that the low-PV water in their cores is a mix of Equatorial Undercurrent (EUC) water and North Equatorial Counter Current (NECC) water. The EUC water is characterized by strong horizontal vorticity, and thus, the baroclinic component of the PV is nonnegligible and acts as a source for the anticyclonic vorticity of TIVs. This horizontal vorticity is tilted by an ageostrophic secondary circulation associated with strain-induced frontogenesis that tends to form along the path of the EUC water that enters the vortex. Frontogenesis disrupts the cyclogeostrophic balance of the frontal flow and drives differential vertical motions across the front. These results emphasize the role of submesoscale physics in the equatorial region, which are active when both the Rossby and Richardson numbers are O(1).

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“…As first noted by Dugan et al (1982), ITE structures are characterized by a subsurface lens of relatively homogeneous water that spans 10-100 km in diameter, and has a vertical extent on the order of 100 m. The lens divides the normal thermocline stratification, with the upper thermocline forming a dome (cyclonic shear) over the top of the lens, and the lower thermocline forming a bowl (anticyclonic shear) defining the base of the lens. The temperature and salinity properties of the ITE are often distinct from those of the regional thermocline, suggesting a remote origin.…”

Section: Intrathermocline Eddymentioning

confidence: 99%