of the two? As a final political as well as scientific point: how large is the effect of shelf-slope processes on climate? Can we show that these effects are significant? Equatorial modellers mostly believe the effects to be negligible.
Day-2: Eddies and Convection, Biogeochemical Processes, and Dense Water Formation
Mac Takahashi and Jackie Grebmeier
Arctic shelves and slopes are important site for exchange and modification of marine-and fresh waters and biogeochemical products that are transported to the Arctic Ocean interior by a variety of processes. Instabilities, eddies, currents, and plume formation influence cross-shelf flux and dispersion of brine-influenced waters to various density layers in the interior ocean at the slope interface. Winter convective plume formation in polynyas and at the developing ice edge have an important influence on dispersion properties for shelf-basin exchange. Sediment entrainment and density flow of water/materials from over the shelf and downslope to considerable depths indicate that canyons may be major conduits for fine sediment fractions and associated carbon loading to the interior. Specific biogeochemical signals are associated with the source water and sediments and may delineate mechanistic properties of this exchange process.
Shelf systems have inherent temporal and spatial variability due to variable oceanic and estuarine processes, including freshwater runoff, ice formation and melt, brine formation, carbon loading, and biological production. Both shelves and slopes have variable geochemical sink and transport modes which influence bioelement (C, N, O) and tracer (Ba, delta O-18) signatures to the slope and interior regions. Plume transport during ice formation is a potential mechanism for shelf-slope-interior exchange. The use of multiple tracers (both active and passive) of physical, chemical, and biological origin were considered essential to delineate offshore and onshore exchange processes. The influence of ice production on dense water formation and subsequent halocline structure directly affects the rates and timing of biological production and associated food chain dynamics.
Topographic steering over the shelf edge and slope is important for both water and material transport. Eddy generation and movement are mechanisms for shelf-basin exchange, and hydrographic sections in the Arctic Ocean interior using a variety of tracers (T S,oxygen,CFCs ) indicate modified shelf water contributions to both near-surface and deep layers. Models indicate eddy-induced transport over the continental shelves, with dense plumes moving over and along the slope.
Important focus questions were delineated during the plenary discussion session, including:
