Observations of Ionospheric Outflow Events as Measured by the Low Energy Neutral 
Atom (LENA) Imager on IMAGE in Association with Variations in the Solar Wind  

H. Khan, M. R. Collier, T. E. Moore
NASA Goddard Space Flight Center, Code 692, Greenbelt, Maryland, MD 20771


The Low-Energy Neutral Atom (LENA) imager on the IMAGE spacecraft was designed 
to observe ionospheric outflow events in the energy range, 10-100eV.  The 
energetic neutrals, created through charge exchange processes involving 
superthermal ionospheric ions and atoms in the exosphere, are imaged by LENA 
and provide an insight into the dynamics of the topside ionosphere and 
interaction of the solar wind with the magnetosphere.  In the study presented 
here, we present several clear enhancements observed by LENA, which originate 
close to the Earth, suggestive of classic outflow events.  These events appear 
to be associated with fluctuations in solar wind pressure and also to variations 
in Dst, as measured by ground magnetometers in the equatorial plane.  We present 
the data in a systematic study to try to understand the generation mechanism for 
the outflow events and to try to charcaterise them to changes in the solar 
wind-magnetospheric environment.  By determining the flux and energy of the 
outflow events, we have a means of associating them to global magnetospheric 
changes.  

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To be presented at the 2002 Spring A.G.U. Meeting, 
Washington, D.C., U.S.A., 28-31 May 2002