Modelling processes influencing shelf edge currents, mixing, across shelf exchange, and sediment movement at the shelf edge

A brief overview, with references to the literature for detail, of a range of physical processes which influence both along and across shelf-edge curr ents and mixing is presented and illustrated by results from a range of num erical models. The importance of internal tides generated both at the shelf edge and at of fshore topographic features in producing local mixing is considered. The in fluence of shelf edge topography off the west coast of Britain and wind dir ection upon along shelf flow and its 'leakage' onto the shelf is examined. In parallel with how oceanic processes can penetrate onto the shelf, the co nditions leading to the interaction of a near shore river plume with a shel f edge flow are investigated. Idealised calculations show that shelf width and location of shelf edge flo w can significantly influence the generation of shelf waves and unstable ed dies in the shelf edge region. The decomposition of the flow field using an Empirical Orthogonal Function approach is found to be a convenient means o f understanding the contribution of both shelf waves and unstable modes. Cross shelf mixing and exchange is examined using both point models, and cr oss shelf models. Calculations show the limitations of a single point model and the importance of the coastline in determining cross shelf circulation . The cross shelf model is also used to examine the distribution of suspend ed sediment under upwelling and downwelling favourable wind conditions. (C) 2001 Elsevier Science B.V. All rights reserved.