DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. The Influence of Buoyancy and Stratification on Circulation, Mixing, and Bottom Stress in Complex Channel/Tidal Flat Systems: A Process Oriented and Realistic Numerical Mode

This effort represents a step towards understanding the dynamics that drive the circulation in estuarine, tidal flat and inner-continental-shelf coastal environments with complex bathymetry, shallow water depths, and strong forcing by tides, river flow, wind and waves, and determining how these circulation patterns and their variability control the pathways of transport of waterborne materials – including sediments, nutrients and anthropogenic materials – through these regions and into the adjacent coastal ocean. Specifically, we aim to develop realistic, high-resolution numerical simulations of such environments that resolve the bathymetric variability and are capable of simulating small-scale coherent structures (for example, flow separation, eddies, and secondary flows) that regulate dispersion and transport of materials within these systems. Essential to this effort is validating such models through skill assessment via statistical comparisons between model output and field measurements over a broad range of forcing conditions. OBJECTIVES The principle objective of this effort is to develop a high-resolution numerical simulation of the Skagit River delta (Fig. 1a), in Puget Sound, Washington – a complex region with broad tidal flats and complex channel networks and one of the focal systems of the ONR Coastal Geosciences Tidal Flat