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Meso-scale eddies in the Nordic Seas - Spatiotemporal variability and their relation to deep-sea convection investigated by use of Lagrangian surface drifters
Anvender-tonings projekt kombineret med geografi, 3. modul, 2000, id:166
Vejleder:Tage Christensen Peter Frederiksen
Findes på RUb:ja
English abstract
Properties of meso-scale eddies (1-100km) in the Icelandic, Norwegian, anf Greenland seas are investigated using trajectories of satellite tracked surface drifters released during 1991-1995 within the SACLANTCEN and ESOP programmes. The data set comprises 35.000 buoy days and allows the separation of the seasonal mean circulation and the meso-scale eddies. Their context is investigated through the structure and variability of the surface circulation. We find barotropic currents driven by the Icelandic atmospheric low to be important with a corresponding winter intensification of most of the internal circulation. The regional distribution of the size of the eddies scales approximately with three times the Rossby radius of deformation ( ,\ 1) as derived from climatological hydrographic data by Chelton et al. [1998]. We argue that significant variability in the radii are present due to winterly breakdown of stratification caused by convection in the Greenland Sea and possibly north of Iceland. High levels of eddy kinetic energy are found in the regions of strong current shear associated with topographic obstacles and especially in the frontal regions separating the Atlantic and Artic domains. Individual drifter tracks in the Greenland Sea are studied to indentify meso-scale eddy structures associated with deep reaching convection. We provide an example of an eddy formed by baroclinic instability at the rim of a convected cold patch reported at depth in the winter of 1994 by Lherminier et al. [1999]. This patch is additionally traced at surface in this data set which lead us to conclude that the use of surface drifters combined with additionally data, can be use to investigate convectional events.

Database opslag den: 25-01-2021