-How is shelf-basin exchange, including particulates, influenced by ice transport, and what are the temporal and spatial scales? - What are the mechanisms for both offshore transport of shelf waters to the interior and compensatory onshelf movement of water from the basin? - What are the processes for selective withdrawal and intrusions of interior water onto the shelf in response to dense water outflow, and what causes temporal and spatial variability in these processes? - What is the role of topographic steering on water exchange? - What is the role of canyons in water exchange, and of sediment-induced turbidity currents in transporting materials (sediment, carbon, bioelements) to the ocean interior?
- How does the shelf replenish itself,and do we have tracers that could track processes, both spatially and temporally? - Can biological tracers (e,g., zooplankton) act as passive tracers for onshore currents?
- What are the requirements for experiments to field test models, and for observational studies designed to understand shelf-break dynamics and transport processes.
Day-3 : Modeling, Sea Ice Processes and Climate
K. Aagaard and M.Ikeda
The first part of the session was concentrated on numerical modelling. The models were rather idealized ones aiming to understand specific physical processes important for shelf-basin interactions. Mesoscale phenomena are believed crucial to cross-shelf transport of momentum, heat, salt and biogeochemical materials. As dense water forms in a near-shore area due to brine rejection, a density front develops and becomes unstable. Baroclinic instability was suggested to be most responsible for meander development, while other instability mechanisms (barotropic and Kelvin-Helmholtz) may play roles also. Tanaka modeled shelf-edge processes such as mesoscale eddy formation and near-bottom boundary layer friction, using a nonhydrostatic numerical model. Akitomo considered stresses between sea ice and the ocean and suggested the modification of a frontal jet over the shelf break: the ice-ocean stress tends to reduce a vertically integrated current and enhance a near-bottom current. Thus, a combination of mesoscale processes and boundary layer dynamics are important for driving along-shore currents.
Fukamachi used an one-and-half-layer model that received freshwater from melting ice during the warm season. A front produced near the ice edge meandered because of baroclinic instability. Therefore mesoscale phenomena play important roles also during ice melting. Convection is a crucial processes associated with dense water
