Large variations in potential vorticity at small spatial scales in the upper ocean

Pollard, Raymond T; Regier, L. A.

doi:10.1038/348227a0

Cited by 54 publications

(38 citation statements)

References 11 publications

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“…(9), which contains the most important result concerning SST, whenever a QG flow is present. This result, which relates SST to subsurface temperature and vorticity is akin to the suggestion by Pollard and Regier (1990) that QG potential vorticity is the key to the physics of the structure of the surface layer, although it is proven here that more relevant quantities are actually the depth-integrated components of potential vorticity, which are respectively, the depth-integrated QG vortex stretching (i.e., subsurface temperature) and depth-integrated relative vorticity, and that the dynamics depend on the local Burger number.…”

Section: Resultssupporting

confidence: 73%

“…), Pedlosky, 1987) and a the thermal expansion coefficient. Using these two relations, (7) can be written as: The order of magnitude of the SST variability is directly proportional to the Rossby number E. Moreover (9) shows that, when a] -a2' the SST variability should resemble the potential vorticity of the QG flow vertically integrated over the surface layer, thus reinforcing the findings of Woods (1988) and Pollard and Regier (1990). However reality is more complex: SST variability is clearly linked to the vorticity and to the stretching of the QG flow in the surface layer, but the relative influence of the two strongly depends on the coefficients al and a2' i.e., on the amplitude of the ML deepening.…”

Section: Journal Of Marine Researchsupporting

confidence: 57%

“…This is all the more important in that quantitative effects of these dynamical properties are underestimated in the QG approximation: it was shown in both KH88 and the present study that the magnitude of the ML variability is directly proportional to the Rossby number and yet, despite this restriction, the amplitudes of the ML variability for SST and ML depth were found numerically to be non-negligible. It is therefore natural to wonder to which extent these results will be quantitatively enhanced or if they will saturate, for dynamical regimes with Rossby number of order 0 (1), such as those commonly observed in surface layers data (Pollard and Regier, 1990). Moreover, one may wonder if the mechanisms described here are qualitatively robust to large excursions of the Rossby number.…”

Section: Resultsmentioning

confidence: 97%

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The mesoscale variability of the sea surface temperature: An analytical and numerical model

Klein¹,

Hua²

1990

j mar res

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This study examines the emergence and evolution of a mesoscale sea surface temperature (SST) variability induced by a uniform and impulsive wind stress when an embedding quasigeostrophic (QG) flow is present. The SST variability which is triggered by the mixed-layer deepening closely resembles some characteristic properties of the QG flow, namely either the subsurface temperature or relative vorticity, depending on the amplitude of the deepening. The SST variance can have the same order of magnitude as the subsurface temperature variance. Within 10 days, the SST field, which is stirred only by the horizontal QG flow, displays a rapid spectral evolution characterized by the emergence of small-scale structures and the appearance of thermal fronts located in the QG jet areas. This evolution depends only on the deformation of the large-scale structures of the SST field, initially resulting from the mixed-layer deepening, by the QG strain field. In contrast with SST, later evolution of the mixed-layer depth is characterized by the emergence of large-scale structures. From these dynamical results, it is speculated that, when nonuniform initial conditions are considered, the resulting SST spatial variability should be more closely related to the subsurface temperature and the SST variance could be significantly increased.

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Section: Resultssupporting

confidence: 73%

Section: Journal Of Marine Researchsupporting

confidence: 57%

Section: Resultsmentioning

confidence: 97%

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The mesoscale variability of the sea surface temperature: An analytical and numerical model

Klein¹,

Hua²

1990

j mar res

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“…Considerable variability and patchiness in the distribution of phytoplankton populations have been observed in regions where nutrient-rich water is carried up into the mixed layer of the oceans (Gower, Denman & Holyer, 1980;Pollard & Regier, 1990). These respond to the motion of water masses of different temperature and salinity as isolation of surface water results in declining phytoplankton populations through nutrient consumption, whereas active vertical water motion results in increasing populations through nutrient recovery.…”

Section: D Final Remarksmentioning

confidence: 99%

Phytoplankton from the Lower Cambrian Læså formation on Bornholm, Denmark: biostratigraphy and palaeoenvironmental constraints

Moczydłowska

Vidal

1992

Geol. Mag.

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Acritarchs from the Lower Cambrian Laesa formation on Bornholm, Denmark, are taxonomically diverse. Their state of preservation, including thermal, mechanical and chemical alteration, is discussed. Different states of thermal maturation of acritarchs in shales and phosphorites of the Broens Odde member could be explained in terms of possible irradiation from natural radioactive decay. The microfossils form two age-diagnostic assemblages that allow recognition of the Skiagia ornata-Fimbriaglomerella membranacea and Heliosphaeridium dissimilare-Skiagia ciliosa Assemblage Zones within the Broens Odde member of the Laesa formation. Acritarch-based biostratigraphy indicates that the Lower Cambrian Balka Formation and Laesa formation correspond to the Schmidtielhis mickwitzi Zone and Holmia kjerulfi Assemblage Zone recognized in Baltoscandia and the East European Platform. Acritarch distribution within three different depositional settings indicates that comparable spectra of morphotypes occurred in different depositional environments. This suggests the absence of facies control. During early Cambrian times palaeoenvironmental barriers in shallow, epicontinental shelf basins constituted a minor obstacle for widespread distribution of acritarch taxa. Formerly proposed early Palaeozoic acritarch provincialism appears insufficiently documented in the fossil record and no evidence could be extracted from the Cambrian record. Following a rapid radiation at the onset of the Phanerozoic, Cambrian phytoplankton populations underwent dispersion following oxygenic and nutrient-rich bodies of water within epicontinental and presumably basinal environments. Lower Cambrian acritarch taxa were largely cosmopolitan and little affected by lithofacies associations. A continuous flow of data is contributing to the emergence of acritarch-based biostratigraphy. Its apparent consistency suggests great usefulness for interregional and detailed event correlation.

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“…The results of this study are valid for the upper layers of the ocean at midlatitude, where the inertial energy is large, and for small-scale energetic eddies such as those observed by Pollard and Regier (1990) and Rudnick (2001). To extend their robustness, it is necessary to explore a larger region of the parameter space and in particular to consider smaller horizontal diffusivity.…”

Section: Resultsmentioning

confidence: 99%

Emergence of cyclonic structures due to the interaction between near‐inertial oscillations and mesoscale eddies

Klein

Hua

Carton

2003

Quart J Royal Meteoro Soc

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Large variations in potential vorticity at small spatial scales in the upper ocean

Cited by 54 publications

References 11 publications

The mesoscale variability of the sea surface temperature: An analytical and numerical model

The mesoscale variability of the sea surface temperature: An analytical and numerical model

Phytoplankton from the Lower Cambrian Læså formation on Bornholm, Denmark: biostratigraphy and palaeoenvironmental constraints

Emergence of cyclonic structures due to the interaction between near‐inertial oscillations and mesoscale eddies

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