Timing of Substorm Signals in the Plasma Sheet and the Auroral Region

Wang, X.Y, J. D. Perez, P. C:son Brandt, D. G. Mitchell, J.-M. Jahn, 
C. J. Pollock, P. Valek, S. B. Mende

Both the Medium Energy Neutral Atom (MENA) and High Energy Neutral Atom
(HENA) imagers onboard the IMAGE spacecraft have been able to observe ENA
emissions from the plasma sheet.  The MENA observations showed enhanced
emissions associated with high solar wind densities during magnetospheric
storm intervals.  The HENA observations showed decreases of emissions from
the plasma sheet following dipolarization associated with substorms.  We
present forward modeling of ENA emission from the plasma sheet using the
Tsyganenko plasma sheet model.  In the model it is found that assuming a
flow velocity toward the Earth of the plasma sheet plasma has a strong
effect on the strength of the modeled ENA flux. Thus the ENA observations
are used to infer the timing of the plasma sheet flow relative to the
substorm signal seen in the FUV imager onboard IMAGE.

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Presentation, Fall Meeting, American Geophysical Union, San Francisco, USA, 
8-12 December 2003