. 1997. Formation and export of water masses produced in Arctic shelf polynyas -process studies of oceanic convection. -ICES Journal of Marine Science, 54: 366-382.The contribution of brine-enriched bottom water from Arctic shelves to intermediate and deep water masses of the adjacent Arctic Ocean or the Nordic Seas is a widely discussed topic in Arctic Oceanography. This paper presents an overview of processoriented modelling which was conducted to deepen our understanding of oceanic convection and its role in water mass formation. It arrives at a conceptual picture of the convective formation of bottom water masses in Arctic shelf seas as a consequence of ice-ocean interactions and considers the role of sediments in slope convection. To investigate and discuss the processes which take part in transformation, production and export of dense shelf water masses a hierarchy of numerical models of different type and spatial resolution was applied. The models cover spatial scales from well below the internal Rossby radius of deformation up to the mesoscale. International Council for the Exploration of the Sea

In the present paper a hydrostatic ''reduced gravity'' model, generally used to simulate transient bottomarrested gravity plumes, was coupled with a sediment transport model. The coupled model considers the respective contribution of suspended sediment particles on the buoyancy of a plume and allows one to simulate autosuspension and size-differential deposition of sediments based on the local turbulence and settling velocities. Simulations using the coupled model reveal that sediment-enriched plumes are able to inject both entrained and original shelf water masses into intermediate and bottom layers of an adjacent ocean basin in an ageostrophic dynamical balance. Hence the mechanism described here is more rapid than classic, ''seawater'' plumes, which are solely driven by surplus density of the water masses. Results suggest that ''turbidity'' plumes may constitute an important process in the formation and renewal of deep waters in the Arctic Ocean. In case a turbidity plume reaches its level of equilibrium density, deposition of suspended particles causes the density of the interstitial fluid to be lower than the density of the ambient fluid. This initiates upward convection within the water column.The substantial difference between TS-and turbidity plumes is described by model experiments that utilize idealized slope and sediment distributions. A realistic simulation of a turbidity plume cascading down the continental slope of the western Barents Sea is presented. The computed distribution of deposited sediments agrees well with observations in an area of high accumulation of shelf-derived sediments. The frequency of occurrence of sediment-enriched gravity plumes originating from the Barents Sea shelf is estimated from the various geological variables (thickness of sediments at the bottom, grain size composition) measured from bottom sediments samples.

Recent investigations on deep water renewal point to the important role of dense water formed on the continental shelves surrounding the Arctic Ocean. In this investigation a hydrostatic, reduced gravity, primitive equation model for the simulation of the spatial and temporal evolution of gravity plumes on a continental slope is applied and compared to the observed outflow of a plume of dense water, originally formed in Storfjorden (Svalbard), into the Greenland Sea toward Fram Strait. The vertically integrated, nonlinear, rotational model accounts for the entrainment of water mass properties from a spatially structured but stagnant ambient water body. This study reveals that part of the dense water, in accordance with earlier estimates, spreads northward along the eastern side of Fram Strait. Another branch of the plume, guided by the topography, flows into a deep trench east of the Knipovitch Ridge to the west of Svalbard. During its descent to depths of more than 2000 m the plume entrains three different water masses (East Spitsbergen Water, Atlantic Water, and Norwegian Sea Deep Water) and hence changes its water mass characteristics. The volume of deep water produced by the mechanism discussed here depends not only on the amount of initially formed brine‐enriched shelf water, but also on the water mass characteristics of the latter.

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