Thin Current Sheets and the Evolution of Auroral Forms

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Thin current sheets are a ubiquitous phenomena in a wide variety of plasma environments. This project will examine processes which drive the dynamic evolution of thin current sheets in the region where the auroras are generated. The dynamic evolution of auroral arcs is responsible for the rapid kinking, curling and folding of auroral forms that make watching the aurora so compelling. These motions are the consequence of the interaction of plasma instabilities in thin current sheets operating on scale sizes from small-scale kinetics up to the size of the full auroral acceleration region. This project will exploit observations from the Reimei spacecraft which provides the first dedicated imaging of auroral forms with magnetically conjugate high time resolution measurements of the particles which drive them. These observations provide the unprecedented opportunity for quantitative analysis of auroral motions and structuring to be performed while simultaneously providing details of the particle distributions driving the optical emissions. The project will implement a new wavelet-based technique for the analysis of sequences of auroral imagery from the Reimei spacecraft to ascertain the vorticity of plasma flows as a function of scale. The distribution of vorticity with current or energy flux (luminosity) will provide the means to identify which processes dominant in the evolution of the auroral structures. The satellite observations will be aided by the use and further development of a 3-D, reduced MHD numerical simulation that includes electron inertia and ionospheric resistivity. Existing statistical field measurements from the FAST spacecraft will be used to augment the Reimei imager and particle observations to provide a more complete characterization electrodynamics of the auroral forms and for comparison with simulation results. The project will help improve our understanding of a very well known and commonly observed phenomenon of public interest. It involves a collaboration with the Center for Science Education at the UC Berkeley Space Sciences Laboratory. The results from this research will be incorporated into a series of workshops for teachers who are primarily involved in teaching African-American and Latino students. The project also promotes teaching, training and learning by providing support for a postdoctoral scholar and graduate student researcher.