Comparison of finite difference and element models of internal tides on the Malin–Hebrides shelf

Hall, Philip; Davies, Alan M.

doi:10.1007/s10236-005-0018-1

Cited by 10 publications

(5 citation statements)

References 31 publications

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“…Surface currents are enhanced and strongly baroclinic over the HTS 41 , the abrupt topography of which generates an internal tide 41 42 that is strongly displaced in two zones centered on the 600 m and 1200–1600 m water depth contours 43 . Given the high density and diversity of large suspension-feeding fauna strictly on the flanks, our biological and CTD data support the notion of this internal tide delivers higher concentrations of particles to the seamount flanks ( Figures 2 , 3 ) than at the summit, which in turns substantially alters species composition between summit and flanks.…”

Section: Discussionmentioning

confidence: 99%

Environmental variability and biodiversity of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic)

Henry

Vad

Findlay

et al. 2014

Sci Rep

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We present the first remotely operated vehicle investigation of megabenthic communities (1004–1695 m water depth) on the Hebrides Terrace Seamount (Northeast Atlantic). Conductivity-temperature-depth casts showed rapid light attenuation below the summit and an oceanographic regime on the flanks consistent with an internal tide, and high short-term variability in water temperature, salinity, light attenuation, aragonite and oxygen down to 1500 m deep. Minor changes in species composition (3–14%) were explained by changes in depth, substratum and oceanographic stability, whereas environmental variability explained substantially more variation in species richness (40–56%). Two peaks in species richness occurred, the first at 1300–1400 m where cooler Wyville Thomson Overflow Water (WTOW) mixes with subtropical gyre waters and the second at 1500–1600 m where WTOW mixes with subpolar mode waters. Our results suggest that internal tides, substrate heterogeneity and oceanographic interfaces may enhance biological diversity on this and adjacent seamounts in the Rockall Trough.

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Section: Discussionmentioning

confidence: 99%

Environmental variability and biodiversity of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic)

Henry

Vad

Findlay

et al. 2014

Sci Rep

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“…Consequently, a change in grid resolution from coarse to fine is desirable in such regions. In addition, stratification effects, associated with the oceanic pycnocline intersecting the shelf slope, can give rise to short wave internal tides (baroclinic tides), which need to be resolved on a higher resolution mesh in the shelf-edge region (Hall and Davies 2005). As shown by Xing and Davies (1997), upwelling and downwelling favourable winds can change the stratification in the shelf-edge region, which in turn changes the distribution of the internal tide and oceanic mixing in this region.…”

Section: Introductionmentioning

confidence: 97%

“…This requires the application of an unstructured grid model (e.g. Hall and Davies 2005) in order to enhance resolution in such regions and enable the large-scale ocean models to take account of these areas of enhanced mixing.…”

Section: Introductionmentioning

confidence: 99%

Modelling the influence of small-scale effects upon the larger scale: an oceanographic challenge

2010

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The problem of resolving or parameterising small-scale processes in oceanographic models and the extent to which small-scale effects influence the large scale are briefly discussed and illustrated for a number of cases. For tides and surges in near-shore regions, the advantages of using a graded mesh to resolve coastal and estuarine small-scale features are demonstrated in terms of a west coast of Britain unstructured mesh model. The effect of mesh resolution upon the accuracy of the overall solution is illustrated in terms of a finite element model of the Irish Sea and Mersey estuary. For baroclinic motion at high Froude number, the effect of resolving small-scale topography within a non-hydrostatic model is illustrated in terms of tidally induced mixing at a single sill, or two closely spaced sills. The question of how to parameterise small-scale nonlinear interaction processes that lead to significant mixing, in a form suitable for coarser grid hydrostatic models, is briefly considered. In addition, the importance of topographically induced mixing that occurs in the oceanic lateral boundary layer, namely, the shelf edge upon the large-scale ocean circulation is discussed together with the implications for coarse grid oceanic climate models. The use of unstructured grids in these models to enhance resolution in shelf-edge regions in a similar manner to that used in storm surge models to enhance near coastal resolution is suggested as a suitable "way forward" in large-scale ocean circulation modelling.

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“…The advantages of using finite elements to compute the M 2 component of the internal tide in a shelf edge region with off shelf seamounts was examined by Hall and Davies (2005a), (hereafter referenced as HD05a). To make a comparison with a fine resolution (2.4 km across shelf and 4.6km along shelf) finite difference internal tide model, (XD98), HD05a used a range of finite element meshes to compute the internal tide off the west coast of Scotland.…”

Section: Introductionmentioning

confidence: 99%

Internal tide modelling and the influence of wind effects

Hall

Davies

2007

Continental Shelf Research

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Initially the development of shallow sea three-dimensional barotropic tidal models is briefly reviewed with a view to determining what were the key measurements that allowed progress in this field and rigorous model validation. Subsequently this is extended to a brief review of baroclinic tidal models to try to determine a way forward for baroclinic model development. The difficulty of high spatial variability, and wind influence are identified as possibly important issues that must be considered in validating baroclinic tidal models. These are examined using a three-dimensional unstructured grid model of the M2 internal tide on the shelf edge region off the west coast of Scotland. The model is used to investigate the spatial variability of the M2 internal tide, and associated turbulence energy and mixing in the region. Initial calculations are performed with tidal forcing only, with subsequent calculations briefly examining how the tidal distribution is modified by down-welling and up-welling favourable winds. Calculations with tidal forcing only, show that there is significant spatial variability in the internal tide and associated mixing in the region. In addition, these are influenced by wind effects which may have to be taken into account in any model validation exercise. The paper ends by discussing the comprehensive nature of data sets that need to be collected to validate internal tidal models to the same level currently attained with three dimensional barotropic tidal models.

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Comparison of finite difference and element models of internal tides on the Malin–Hebrides shelf

Cited by 10 publications

References 31 publications

Environmental variability and biodiversity of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic)

Environmental variability and biodiversity of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic)

Modelling the influence of small-scale effects upon the larger scale: an oceanographic challenge

Internal tide modelling and the influence of wind effects

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