Localized ion outflow in response to a solar wind pressure pulse

S. A. Fuselier, H. L. Collin, A. G. Ghielmetti, and E. S. Claflin
Lockheed Martin Advanced Technology Center, Palo Alto, CA, USA

T. E. Moore and M. R. Collier
NASA Goddard Space Flight Center, Greenbelt, MD, USA

H. Frey and S. B. Mende
Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA, USA


 Neutrals created by charge-exchange of low-energy (~10 - 100 eV) ion outflow from
the ionosphere are imaged by the Low Energy Neutral Atom (LENA) imager on the
IMAGE spacecraft. Comparing the neutral flux with changes in the solar wind during 
an ion outflow event on 24 June 2000 indicates that changes in solar wind density 
(and therefore dynamic pressure) are associated with episodic bursts of ion 
outflow. LENA images show that these bursts are confined to the duskside. 
Simultaneous images of the aurora from the IMAGE FUV Wideband Imaging Camera 
indicate that these episodic bursts on the duskside are associated with increased 
duskside auroral emissions. The pitch angle and charge exchange altitude for the 
ion outflow distributions are estimated by applying field line tracing in a model 
magnetic field and assuming that the outflow occurs in the auroral zone. The pitch 
angle information places constraints on the neutral atom images, indicating that 
the ion outflow observed on the duskside probably consists of high pitch angle 
conics and that field-aligned ion outflow from other parts of the oval cannot be 
observed from the IMAGE spacecraft location. 

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Journal of Geophysical Research, 107, A8, 10.1029/2001JA000297, SMP 26-1, 2002.