Collaborative Research: The internal Surfzone: Wave-averaged circulation driven by nonlinear internal waves shoaling over spatially-varying bathymetry

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Transport by nonlinear internal waves in coastal regions has strong interdisciplinary ties to biological oceanography through transport of plankton and nutrients; geological and geochemical oceanography via transport of sediments; and coastal engineering/management via transport and dispersion of anthropogenic materials such as effluent from sewage outfalls. The overall objectives of this study are to understand the dynamics governing the flux of momentum from shoaling nonlinear internal waves to mean currents; the scale and structure of mean flows driven by shoaling internal waves under idealized conditions; and the magnitude and spatial structure of the net mass transport associated with the shoaling internal waves. Despite the ubiquitous nature of nonlinear internal waves in the coastal ocean, very few three dimensional studies exist that include variability of the topography in the direction normal to propagation. This study represents the first attempt to quantify the transport pathways forced by internal waves and the mean flows generated by them and it is expected to produce results and methodologies with broad applicability in interdisciplinary oceanography and coastal management. The project will support the professional development of a postdoctoral researcher and a graduate student. The approach is based on a state of the art, three-dimensional, non-hydrostatic numerical model with adaptive mesh capabilities. In addition, data previously collected in Massachusetts Bay during previous studies will be analyzed. This is the first study to systematically address the mean flow and transport driven by nonlinear internal waves shoaling over bathymetry varying in two dimensions. The study comprises two components: a modeling component used to study the transfer of momentum and water mass transport in a variety of situations of increasing realism, and a data-analysis component which will consider the same problem using the extensive dataset available from a series of experiments conducted in Massachusetts Bay over the last 16 years. The modeling component will be used to aid in interpreting the data. The model (Stratified Ocean Model with Adaptive Refinement), developed in part with funding from previous National Science Foundation proposals, is a state-of-the-art three-dimensional non-hydrostatic stratified ocean model which employs adaptive mesh refinement to effectively use the computational resources, increasing resolution on demand where necessary.