Dayside Aurora Dynamics

S.-W. Chang, J. F. Spann, S. B. Mende, and R. P. Lepping

Images from the FUV instrument on board the IMAGE spacecraft will be presented
to demonstrate the auroral dynamics in the dayside auroral zone and the polar
cap region. Optical emissions detected by three different detectors of FUV
come from precipitations of energetic protons, electrons, and both species,
respectively. In general, auroral activities in these regions responded very
well to variations in the boundary conditions either external or internal to
the magnetosphere, i.e., in the solar wind or the magnetotail. As a result,
auroral images from FUV provide an excellent tool to investigate particle
acceleration and transport processes within the geospace, such as shock
acceleration, substorm injections, etc. We will interpret the observed
auroral images using various models, discuss difference and similarity in the
auroral activity from several typical cases, and assess conditions optimal to
each type of auroral activity.