Research in Linear and Nonlinear Instability and Ocean Circulation Theory

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The project consists of two themes: (1) Ocean Circulation Theory, in particular the flow around planetary scale islands including the effects of topographic "skirts" to the island, and (2) the linear and nonlinear dynamics of instabilities.In the context of the first theme the investigator, Dr. Pedlosky, will examine the nature of the circulation around islands and similar topographic features when topography produces closed, ambient, geostrophic contours of potential vorticity around the island. Preliminary investigation has demonstrated the strong influence of the topography in trapping fluid in a recirculation around the island and hence altering the measure of the interchange of fluid from one sub basin to another on each side of the island. This issue is of oceanographic and climatic relevance for flows as the Indonesian Throughflow. The process will be studied analytically, numerically and in the laboratory. For the second theme, the investigator will be guiding the research of a graduate student in a study of the instability of the frontal system produced by downwelling favorable wind stress on a coastal shelf. Preliminary results indicate that the resulting eddies can play a significant role in the cross shelf heat and mass transport. Broader Impacts: The proposed work takes up the study of novel and fundamental fluid mechanical processes of direct oceanographic relevance. The results of the research proposed here on the coastal instability problem will have applications to transport of tracers in the coastal zone and thus have ecological as well as dynamical consequences. The research associated with the flow around islands and through narrow gaps, in the context of the Indonesian Throughflow, has relevance to the planetary overturning circulation and hence pertinence to the problem of climate. Part of the research involves the guidance of a Ph.D. graduate student participating in the research (funded on another project) and will serve as a central element in his training and intellectual development. The interaction with Italian colleagues aids in the international exchange of scientific expertise.