Case study of solar wind pressure variations and neutral atom emissions 
observed by IMAGE/LENA

H. Khan, M. R. Collier, T. E. Moore


The Low Energy Neutral Atom (LENA) imager on the IMAGE spacecraft was designed
to observe neutral atom emissions at low energy (10 eVŠ ~4 keV) from the
high-latitude ionosphere. In this study we present data from an ion outflow
event on 24 June 2000 showing increases in neutral flux that appear to be
associated with dynamic pressure variations in the solar wind. Results from a
correlation analysis show the neutral flux to be well correlated (`0.64) with
the solar wind dynamic pressure. The neutral atom data are most consistent with
a source region at a radial distance of 2.2Š2.3 RE, interpreted as the region
over which the bulk ion outflow escapes the ionosphere and is partly converted
to neutral atoms. Very short time delays (~2 min) were calculated between the
solar wind pressure increase and neutral atom response, indicating a prompt
ionospheric response to the solar wind input. 

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Journal of Geophysical Research, 108(A12), 1422, doi:10.1029/2003JA009977, 2003