Low altitude ENA emissions observed from various vantage points on IMAGE

C.J. Pollock, J. Jahn, and A. Isaksson
Southwest Research Institute, San Antonio, TX


Interaction between the atmosphere and proton precipitation from the ring
current results in proton ENA emission into space, due to an effective
reflection from the atmosphere. Observation of this emission from the orbiting
IMAGE spacecraft is strongly dependent upon the location of the spacecraft,
because the emission is non-isotropic and the flux of reflected ENAs is
therefore non-homogeneous in space. We have presented observations of reflected
ENAs taken when IMAGE was at relatively low altitude. In this paper we will
present results from a wider range of IMAGE altitudes. We present latitude
distributions of the reflected ENA source along with estimates of the pitch
angle distributions at the source location. We will discuss these results in
terms of the reflection process and what we can learn about the proton
precipitation by studying the reflected ENA distributions.

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Presentation, Fall A.G.U. Meeting, San Francisco, CA, 13-17 December 2004