Spence, H. E.,
Co-Authors: J. B. Blake, M. G. Henderson, A. M. Jorgensen, and G. D. Reeves,
Title: Energetic neutral atom imaging of the Earth's magnetosphere: NASA/POLAR spacecraft results,
Reference: Presented at the 40th Annual Meeting of the Division of Plasma Physics of the American Physical Society, New Orleans, 16-20 November, 1998, Bulletin of the APS, Vol. 43, No.8, page 1817, 1998.
Reference Type: Invited Talk
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Abstract:
The NASA POLAR spacecraft has been routinely measuring energetic neutral atoms (ENAs) on a global scale from its high apogee (9 $R_E$), polar orbit. POLAR can identify ENAs when it is in a region of low ion flux. This occurs during large portions of its orbit when it dwells in the high latitude magnetospheric lobes. We find that significant ENA signals from the inner magnetosphere are recorded even during periods of magnetic quiesence when the main source of ENAs, the ring current, is nearly in a resting state. While the ENA data stream is not strictly continuous (it is interrupted when POLAR passes through hot ion populations), we have compiled a comprehensive data base from which long term trends may be tracked. We show that the recently-described ENA metric ({it Jorgensen et al.}, 1997), the Global Energetic Neutral Index (GENI), can be used to gauge storm activity over extended periods. We shall present the GENI index and associated ENA images for several events and demonstrate both the temporal and spatial information provided by this novel magnetospheric imaging technique.
