Substorm Injections as Observed using Global Energetic Neutral Atom (ENA) Imaging

Pollock, C. J., P. C:son Brandt, J. L. Burch, M. G. Henderson, J.-M. Jahn, 
D. J. McComas, D. G Mitchell, J. D. Perez, G. D. Reeves, R. M. Skoug, M. Thomsen, 
and P. Valek,

We review recent progress that has been made, using global ENA imaging of the
magnetosphere, in the area of the substorm particle injections, their timing and
dispersion, and their impact on storm time ring current growth. One area where
recent modeling and global imaging have made substantial progress recently is in
understanding the important role of enhanced magnetospheric convection to the
formation of the storm-time ring current. Under conditions of enhanced
convection, the ring current tends to remain highly asymmetric, with injected
ions flowing out the day side and lost down stream. Under these conditions,
individual substorm injections do not provide major contributions to the
long-term growth in ring current energy content. On the other hand, continual
injection of particles onto low L-shells where trapping may occur can produce
long-term ring current growth. One area where substorms can make an important
contribution to storm growth is by extracting oxygen from the ionosphere. This
oxygen is then efficiently energized and then injected into the inner
magnetosphere, where it can make strong contribution to the ring current energy
content. Examples of observations of these phenomena will be presented and their
significance in the storm/substorm relationship will be reviewed.

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To be presented at the Magnetospheric Imaging Workshop, 
Yosemite National Park, California, U.S.A., Feb. 5-8, 2002.