What the LENA data tells us about high latitude ion energization: 
Model data comparisons

G. R. Wilson (Mission Research Corporation, One Tara Blvd., Suite 302, 
              Nashua NH 03062; 603-891-0070 x 242; gwilson@mrcnh.com),
T. E. Moore, M. Collier (Code 692 -Interplanetary Physics NASA/Goddard 
                         Space Flight Center Greenbelt, Maryland 20771)

The LENA instrument on the IMAGE spacecraft measures low energy (10-300 eV) 
neutral atoms originating from, among other places, the auroral ionosphere.  
It produces six two-dimensional images (for three energy bins and two masses) 
at 8û angular resolution every two minutes.  Images of the high latitude 
ionosphere made during IMAGE perigee passes indicate that the neutral flux 
levels, their dependence on magnetic activity, and their peak production being 
below 1500 km altitude are in rough accord with preflight estimates.  However, 
to no ones surprise, details of the images do not conform to expectations.  
Principle among these discrepancies is the lack of a clearly defined auroral 
oval in the images.  To properly interpret the images we have redone much of 
our previous analysis.  This includes the use of an improved empirical ion 
outflow model that has been adjusted to be consistent with the results of the 
numerous statistical studies of outflow data.  In addition we have added to the 
calculations, processes that specifically effect the transport of low energy 
neutrals originating at low altitudes, namely, collisions, gravitational 
deflection, and ram deflection. These latter effects seem to be key to properly 
understanding the LENA perigee images.

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Submitted to the Spring 2001 AGU Meeting, Boston, Massachusetts