Magnetosheath Neutral Atom Observations and the Relationship With Radar
Backscatter in the Cusp: Combined Observations From IMAGE LENA and SuperDARN

H. Khan, M.R. Collier, T.E. Moore, M. Lester, S. Taguchi, K. Hosokawa


In this study we present preliminary observations showing the relationship
between charge exchanged neutral atom emissions from the magnetosheath and the
appearance of cusp-like signatures in the ionosphere. The Low Energy Neutral
Atom imager on IMAGE can be used to detect the magnetosheath neutral atom
signature during strong southward IMF conditions. Correspondingly, under such
conditions, dayside reconnection is enhanced and the ground based SuperDARN
radars monitor the increase in the flow and backscattered power associated with
enhanced activity in the cusp. We present data from the SuperDARN radars,
showing typical cusp signatures during the period of enhanced neutral atom
emissions observed by LENA. We show that there is a significant correlation
between the backscattered power at high latitudes detected by the radar and the
ENA emission recorded at LENA. As the magnetopause is eroded due to the
increased reconnection activity, the neutral density near the reconnection site
will be higher than under normal conditions, resulting in a higher flux of
charge exchanged neutral atoms observed by LENA. Also there may be a greater
influx of magnetosheath particles which can charge exchange in the magnetosphere
resulting in an increase in neutral atom emissions observed by LENA. The
particle precipitation also ionizes the high latitude ionosphere producing
irregularities resulting in an increase in the radar backscattered power. We
present the observations showing the relationship between the ENA emissions and
the radar backscatter in the cusp region.

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Presentation, Fall Meeting, American Geophysical Union, San Francisco, USA, 
8-12 December 2003