Variability of currents in Great South Channel and over Georges Bank : observation and modeling

Chen, Changsheng

doi:10.1575/1912/5494

Cited by 25 publications

(18 citation statements)

References 75 publications

(190 reference statements)

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“…This current tends to flow eastward as a jet of $30 cm/s on the northern flank and recirculate westward as a relatively weak, broad current of about 1 -5 cm/s on the southern flank. Previous theoretical and numerical modeling studies suggest that the strong current jet formed on the northern flank is a result of (1) nonlinear interaction of barotropic tidal current with variable bottom topography [Loder, 1980;Greenberg, 1983], (2) seasonal stratification due to surface heating and intensification of the tidal mixing front [Chen, 1992;Naimie et al 1994;Chen et al, , 2001bNaimie, 1996], (3) nonlinear interaction between barotropic and internal tidal currents and between internal tidal currents Beardsley, 1995, 1998], and (4) upstream buoyancy-driven flow [Chapman and Beardsley, 1989;Chapman, 2003].…”

Section: Tidal-rectified Currents On Georges Bankmentioning

confidence: 99%

A finite volume numerical approach for coastal ocean circulation studies: Comparisons with finite difference models

Chen¹,

Huang²,

Beardsley³

et al. 2007

J. Geophys. Res.

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224

138

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[1] An unstructured grid, finite volume, three-dimensional (3-D) primitive equation coastal ocean model (FVCOM) has been developed for the study of coastal ocean and estuarine circulation by Chen et al. (2003a). The finite volume method used in this model combines the advantage of finite element methods for geometric flexibility and finite difference methods for simple discrete computation. Currents, temperature, and salinity are computed using an integral form of the equations, which provides a better representation of the conservative laws for mass, momentum, and heat. Detailed comparisons are presented here of FVCOM simulations with analytical solutions and numerical simulations made with two popular finite difference models (the Princeton Ocean Model and Estuarine and Coastal Ocean Model (ECOM-si)) for the following idealized cases: wind-induced long-surface gravity waves in a circular lake, tidal resonance in rectangular and sector channels, freshwater discharge onto the continental shelf with curved and straight coastlines, and the thermal bottom boundary layer over the slope with steep bottom topography. With a better fit to the curvature of the coastline using unstructured nonoverlapping triangle grid cells, FVCOM provides improved numerical accuracy and correctly captures the physics of tide-, wind-, and buoyancy-induced waves and flows in the coastal ocean. This model is suitable for applications to estuaries, continental shelves, and regional basins that feature complex coastlines and bathymetry.

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Section: Tidal-rectified Currents On Georges Bankmentioning

confidence: 99%

A finite volume numerical approach for coastal ocean circulation studies: Comparisons with finite difference models

Chen¹,

Huang²,

Beardsley³

et al. 2007

J. Geophys. Res.

Self Cite

224

138

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“…Franks (1992) examined several models of swimming behaviour and their potential to create patchiness at different scales. Chen (1992) suggested that convergence in frontal regions of Great South Channel might explain the 2The layer thickness h is limited by the total depth H: h = min(25 m, H) 3Note that the case of net vertical rnigrat~on to the surface layer, e.g. of animals exiting diapause, would be accounted for as a net source and would contribute to R dense aggregations of Calanus observed there.…”

Section: Circulationmentioning

confidence: 99%

Biological/physical simulations of Calanus finmarchicus population dynamics in the Gulf of Maine

Lynch¹,

Gentleman²,

McGillicuddy³

et al. 1998

Mar. Ecol. Prog. Ser.

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A site-specific, coupled biologicaVphysica1 model is described for the dominant winterspring copepod in the Gulf of Maine. The biological portion describes temperature-and fooddependent progression through 13 life stages in an Eulerian (concentration-based) framework. The population is transported in a flow field depicting the climatological mean conditions in 2 mo 'seasons'. Behavioural assumptions account for depth selection and 2 limiting cases are contrasted: dispersal throughout the water colun~n, and aggregation in the surface layer. Simulations are inspired by MARMAP observat~ons, with an emphasis on the mid-winter initiation of the annual bloom by diapausing populations, and their role in supplying reproducing populations to Georges Bank during spring. Passive tracer sirnulations illustrate the role of the circulation. Georges Bank itself is an open system and depends on resupply from external sources. A l l 3 deep basins of the Gulf are capable of contributing populations to the Bank. The Scotian Shelf is capable of populating the Southern Flank. In the case where the organisms aggregate in the surface layer, the effect of convergence in downwelling zones is shown to be a significant contributor to population &stribution. Baseline population dynamics are initiated on January 1 by activating a diapausing population (Go) based on 10 yr mean abundance and distribution from the MARMAP program. The abundance and distribution of Go adults is reproduced with a 3-layer model, spatially vanable mortality, an extended period of activation, no food limitation, and a large, heretofore unobserved source of diapausing C5s near-bottom. Reproduction modeled in this system shows significant development of generation 1 (G,) over the Gulf of Maine in February-March, which is not observed. Delay of reproduction over the Gulf, and/or severe early-stage mortality, is required to conform with the data. The space-time pattern of this effect is consistent with the observed chlorophyll distribution and hming, and reasonable food-limitation thresholds. Inclusion of this effect initiates the spring Calanus bloom in the correct space-time pattern, with significant cohorts of Go females and G, nauplii over important cod and haddock spawning grounds on Georges Bank. The implication is that G, is locally spawned in food-rich waters over Georges Bank by females advected in the food-poor Gulf of Maine surface layer.

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“…Numerical models of tidal flow over rough bottom topography frequently involve advanced turbulence closure schemes, which are based on the turbulent kinetic energy equation and prognostic or diagnostic expressions for a turbulent mixing length (e.g., Davies and Jones, 1990;Chen, 1992;Simpson and Sharples, 1994;Naimie, 1995;. An alternative and computationally more efficient approach is the use of spectral models, which incorporate eddy viscosity parameterizations with specified vertical distribution and time-dependence that is related to the flow field.…”

Section: Introductionmentioning

confidence: 99%

Surface and bottom boundary layer dynamics on a shallow submarine bank : southern flank of Georges Bank

Werner¹

1999

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The thesis investigates the circulation at a 76-m deep study site on the southern flank of Georges Bank, a shallow submarine bank located between the deeper Gulf of Maine and the continental slope. Emphasis is placed on the vertical structure of the bottom boundary layer driven by the semidiurnal tides and the flow field's response to wind forcing.The observational analysis presented here is based on a combination of moored array and bottom tripod-mounted current, temperature, conductivity, and meteorological data taken between February and August 1995. Results from the bottom boundary layer analysis are compared to numerical model predictions for tidal flow over rough bottom topography. The flow response to wind forcing is examined and brought into context with the existing understanding of the wind-induced circulation in the Georges Bank region. Particular attention is given to the vertical distribution of the wind-driven currents, whose variation with background stratification is discussed and compared to observations from open ocean studies.

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Variability of currents in Great South Channel and over Georges Bank : observation and modeling

Cited by 25 publications

References 75 publications

A finite volume numerical approach for coastal ocean circulation studies: Comparisons with finite difference models

A finite volume numerical approach for coastal ocean circulation studies: Comparisons with finite difference models

Biological/physical simulations of Calanus finmarchicus population dynamics in the Gulf of Maine

Surface and bottom boundary layer dynamics on a shallow submarine bank : southern flank of Georges Bank

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