3D turbulence field on the north-western european continental-shelf

in Tellus : Series A (1994), 46(2), 98-112

The 3-dimensional, non-linear, baroclinic, GHER mathematical model for the study of mesoscale motions (time scale of several hours to several days: tides, storm surges, ...) is described. Particular ... [more ▼]

The 3-dimensional, non-linear, baroclinic, GHER mathematical model for the study of mesoscale motions (time scale of several hours to several days: tides, storm surges, ...) is described. Particular attention is paid to the turbulent closure based on an evolution equation for the turbulent kinetic energy and a parametric expression of the mixing length (k-model). Appropriate boundary conditions and numerical techniques (mode-splitting, implicity, sigma-coordinate system, advection scheme) are described. The model is applied to the simulation of the M2 tide on the North-Western European Continental Shelf not only without wind but also in typical winter and summer conditions. Large spatial variations of the turbulent kinetic energy appear as a result of the variations of depth and tidal activity around the shelf. These variations are clearly related to the different turbulence regimes observed in summer, with frontal structures separating well-mixed waters from stratified ones. The structure and evolution of the vertical profiles of turbulence variables are described and explained in barotropic and baroclinic conditions, under different wind forcings. The evolution of these profiles at the M2 tide frequency largely depends on the eccentricity of the tidal ellipse. [less ▲]

PRELIMINARY-RESULTS OF 3-D BAROCLINIC NUMERICAL-MODELS OF THE MESOSCALE AND MACROSCALE CIRCULATIONS ON THE NORTH-WESTERN EUROPEAN CONTINENTAL-SHELF

in Journal of Marine Systems (1992), 3(4-5), 423-440

Two mathematical models for the study of mesoscale (tides, storm surges ...) and macroscale (general circulation ...) motions are described. Both models are derived from the GHER 3-D baroclinic turbulent ... [more ▼]

Two mathematical models for the study of mesoscale (tides, storm surges ...) and macroscale (general circulation ...) motions are described. Both models are derived from the GHER 3-D baroclinic turbulent closure primitive equation model and adapted to the specific spectral windows of, respectively, mesoscale and macroscale processes. Numerical methods are discussed: 3-D finite differences, mode-splitting, sigma-transform ... The mesoscale model is applied to the simulation of the M2 tide on the North-Western European Continental Shelf. The residual circulation model is based on time averaged primitive equations which explicitly include mesoscale Reynolds stresses that are computed by the mesoscale model. Preliminary results of the application of this model in typical summer conditions are presented. [less ▲]