ALBERT

Description: In the framework of the BRIOS ({\it Bremerhaven Regional Ice OceanSimulations}), a three-dimensional tidal model was developed toinvestigate tidal processes in the southern Weddell Sea. Themodel is based on the free surface SCRUM ({\it S-Coordinate Primitive EquationOcean Model}), modified to allow for the inclusion of the horizontalcomponent of the Earth's rotation vector, the equilibrium tide and ice shelves.Barotropic tides are simulated in a regional two-dimensional (x-y) configuration for theAtlantic Sector of the Southern Ocean. In thisinvestigation, the semidiurnal M$_{2}$ and S$_{2}$ andthe diurnal K$_{1}$ and O$_{1}$ frequencies are considered.For both semidiurnal constituents, maxima amplitudes are foundin the southwestern corner of the Filchner-Ronne Ice Shelf (FRIS).Diurnal tides have higher amplitudes at thecontinental shelf break where they excite continental shelf waves ofsame period propagating in the along-slope direction.With the full three-dimensional model, baroclinic tidal currents are studied in the innerWeddell Sea, using an orthogonal curvilinear 3D grid. Semidiurnal and diurnalperiods are considered, although the emphasis is on thesuperinertial frequencies at which free propagating internal tidescan be generated at the latitude range of the inner Weddell Sea. Thevertical structure of tidal currents in the southern continental shelfregion and beneath FRIS are described in detail, including theirseasonal variability. The model results show that tidal currents contributesignificantly to the turbulent mixing at the shelf break of the southern Weddell Seaand beneath FRIS. They also suggest that tides have a direct effecton both water mass formation through mixing and on water massmodification through heat transport to the upper boundary layer, in the iceshelf cavities and by opening leads in the sea ice.

Description: A three-dimensional primitive equation ocean model is used to study themagnitude and distribution of tidal mixing in the southern WeddellSea. The contributions of (a) semidiurnal barotropic constituentsM2 and S2, (b) internal tides, and (c)diurnal barotropic tides are considered. Computedelevation co-tidal charts are generally consistent with our knowledgeand observations for the region. The model reproduces maximum semidiurnal tidalelevations of about 1.6 m and 1.0 m for M2 and S2, respectively. Aninternal tide of moderate strength is generated over the slope,propagating in the along-slope direction but rapidly dissipating. Onthe continental shelf, a thick benthic boundary layer (150 m) developsdue to the proximity of the critical latitude for the M2constituent. Typical M2 and S2 baroclinictidal currents at the shelf break are 10 cm/s and 6 cm/s, respectively.In general, the tidal currents produce strong mixing in the bottom boundary layer at the shelf breakand on the shelf leading to high vertical eddy viscosity/diffusivitycoefficients of up to 0.1 m2/s. Both summer and winter stratification are investigated;increased mixing near the surface is found in summer. The model results suggestthat tides contribute significantly to the turbulent mixing at theshelf break of the southern Weddell Sea.

Description: The role of seamounts in the formation and evolution of sea ice isinvestigated in a series of numerical experiments with a coupled seaice-ocean model. Bottom topography, stratification and forcing areconfigured for the Maud Rise region in the Weddell Sea. The specificflow regime that develops at the seamount as the combined response tosteady and tidal forcing consists of free and trapped waves and aTaylor column, which is caused by mean flow and tidal flowrectification. The enhanced variability through tidal motion inparticular is capable of modifying the mixed layer above the seamountenough to delay and reduce sea ice formation throughout the winter.The induced sea ice anomaly spreads and moves westward and affects anarea of several 100~000 km$^{2}$. Process studies reveal the complexinteraction between wind, steady and periodic ocean currents: allthree are required in the process of generation of the sea ice andmixed layer anomalies (mainly through tidal flow), their detachmentfrom the topography (caused by steady oceanic flow), and the westwardtranslation of the sea ice anomaly (driven by the time-mean wind).

Description: For a complex Banach algebra $E$ , we study the strong dual of the Fréchet space ${\mathcal {H}}_L(E)$ of the mappings $f: E \rightarrow E$ that are analytic in the sense of Lorch. First, we will show that $(\mathcal {H}_L(E)^\prime , \beta )$ is isomorphic to a regular inductive limit of Banach spaces of sequences in the strong dual of $E$ . As a consequence, we will get topological properties of $(\mathcal {H}_L(E)^\prime , \beta )$ and we will show that this strong dual is the inductive dual of $\mathcal {H}_L(E)$ .