The Aurora As Monitor of Magnetospheric Boundary Layer Processes

In a selective review, we report on recent case studies of auroral forms and activities related to different magnetospheric boundary layers. The topics covered include the following: 1) the electron edge of the dayside low-latitude boundary layer (LLBL) (equatorward boundary of southward IMF cusp), 2) sequential LLBL plasma injec- tions ("stepped cusp"), 3) the poleward boundary of the northward IMF cusp and its associated layers of strong flow shear during transition states, 4) filamentation and other structure of the flank boundary layer for various IMF configurations, and 5) the nightside plasma sheet boundary layer during substorm expansion. Implications of the continuous ground based monitoring of these boundary layers from the aurora, in combination with radar ion drift data and particle precipitation data from satellites in polar orbit, will be discussed.