Global Imaging of Proton and Electron Aurora in the Far Ultraviolet

Mende, S. B., H. U. Frey, T. J. Immel, J.-C. Gerard, B. Hubert, S. A. Fuselier

The IMAGE FUV instrument provides for the first time a global simultaneous
view of electron and proton precipitation. Being able to observe protons on
the sunlit dayside is especially significant since it has not been possible to
make ground based optical measurements here. At high latitudes during positive
IMF Bz dayside proton produced auroras were seen whose properties were
consistent with direct proton entry at the high latitude lobe merging site. At
times at lower latitude on the dayside detached proton auroral arcs can be
seen. On the nightside the proton aurora was observed to respond to substorm
activity by intensifying at onset, expanding poleward but only moderately when
compared to the electrons.  In situ observations with the FAST satellite
showed the particle and field character of the various auroral forms seen by
IMAGE FUV during substorm phases. Comparison between IMAGE FUV and energetic
neutral atom (ENA) imager data shows that intense proton and electron
precipitation is a relatively short lived feature of the substorm when
compared to the longevity of the trapped fluxes which had been transported in
during the initial substorm phases.  

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