Observations of circulation and related physical variables have been collected in Bahia Concepcion, on the Gulf of California side of the Baja California peninsula in Mexico. The first goal of the original study was to describe through observations how rotation affects the wind-driven circulation in a relatively deep, well-mixed, semi-enclosed bay. We are in the process of submitting those results for publication. The period of observations, originally planned to last only through the well-mixed winter season, was extended to the entire year, including the highly stratified summer season. The extended data set gives us the opportunity to describe the physics of the bay when the water column is stratified. This study focuses on three separate time scales: the seasonal cycle associated with the onset and demise of stratification, the internal tides, and the barotropic and baroclinic seiches. The second goal of the original study was to develop an analytical model to represent the circulation driven by tides and the effects of friction and rotation on the estuarine flow. Those tasks are now complete. Motivated by the results of the winter observations we propose here to develop analytical models of three-dimensional time-dependent wind-driven flow, including the effect of advection, and to extend the tidal modeling effort to include stratified basins.
Broader Impacts The ecological and societal importance of small coastal basins (bays, estuaries, lagoons) is out of proportion with their size. Among many other important ecological functions, lagoons and estuaries serve as way stations for migrating birds, as nurseries for an immense variety of fauna and flora and as mating and calving grounds for marine mammals such as the Pacific gray whale. At the same time these water bodies have been deeply impacted by anthropogenic activities. Many, if not all, are used as pathways through which sewage and contaminated waters are introduced into the ocean. In the past three years we have developed contacts with and given talks to engineering consultants and lay groups who are stewards of several lagoons in San Diego county. We plan to further develop these associations by providing free advice and consultation. By way of mitigation, The So. Cal. Edison company is undertaking an eighty million dollar restoration of San Dieguito Lagoon, north of San Diego. Here we propose to work with Coastal Environments, the consultancy charged with the scientific management of the project at the same time as we advise the San Dieguito Lagoon conservancy and other advocate groups. This project will allow us to participate in summer hands-on activities with high school students, and continue our outreach efforts with Florida elementary schools. In addition, this study represents a collaboration between scientists from the USA, including a minority representative, and Mexican scientists. The study will continue to enhance the participation of minority groups in science. It will train one graduate student and one Post-Doc and expose many others, including minority undergraduates, to state-of-the-art data collection, analysis and the application of numerical models. It will facilitate international cooperation and capacity building in Mexico and will also greatly enhance the courses taught by the PIs at graduate and undergraduate levels.
