Investigation of Persistent and Coherent Structures in Geophysical and Turbulent Flow

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This research includes theoretical, numerical and observational studies of the free solutions of the equations of fluid motion, with the goal of understanding persistent and coherent structures in the atmosphere and in fluid turbulence. Such structures are ubiquitous features of numerical simulations and of large scale atmospheric flow. Understanding how they evolve and affect the turbulent flow in which they are embedded is fundamentally important in geophysical fluid dynamics, as well as being of practical importance in long range predictability. The PIs have recently discovered potentially powerful methods which enable steady stable solutions to be constructed from an unsteady initial state, while preserving the vorticity structure, or signature, of the initial state. They will utilize such methods in an investigation of observed persistent phenomena in the atmosphere, and to systematically investigate the construction of steady solutions of the equations of motion, for three dimensional, two-dimensional and quasi-geostrophic flow. They will also perform theoretical and numerical investigations of this and related techniques. The general significance of the work is that use of the methods will elucidate the nature of persistent structures in turbulence and in geophysical flow, by relating them to free solutions of the equations of motion. The methods also provide the means to construct new, stable, fluid configurations. Weather and climate systems are manifestations of geophysical turbulence and so this research may lead to improved understanding of these systems.