Spence, H. E.,
Co-Authors: R. B. Sheldon, T. A. Fritz, J. Chen, J. B. Blake, J. F. Fennell, D. N. Baker, M. G. Henderson, M. Grande, M. G. Kivelson, and R. J. Walker,
Title: Polar Energetic Particles (PEPs): A new signature of the high-latitude magnetosphere,
Reference: AGU Fall Meeting, San Francisco, CA, 15-19 December, 1996.
Reference Type: Invited Talk
CEPPAD: true
CAMMICE: true
RAPID: false
Abstract:
A striking first result of the energetic charged particle experiments on the recently launched NASA POLAR satellite is the surprising appearance of energetic ions on high-magnetic-latitude field lines at high altitudes. These unanticipated elevated fluxes of $>$10 keV ions are observed very frequently when the POLAR spacecraft is near apogee (9 R$_E$) in a region not before sampled systematically or comprehensively. We outline the characteristics of the polar energetic particles (PEPs) using observations from the POLAR Comprehensive Energetic Particle and Pitch Angle Distribution (CEPPAD) and Charge and Mass Ion Composition Experiments (CAMMICE). The CEPPAD measurements provide high spectral and pitch angle resolution measurements of ions with high time resolution; CAMMICE provides complementary composition information. Using data from the first six months of POLAR observations, we explore the PEPs occurrence frequency and magnitude and correlate these with solar wind and IMF conditions, as well as with other POLAR instruments. The most prominent PEPs are of solar wind origin, occur during predominantly northward IMF, and are observed in regions predicted to lie deep within the magnetotail lobes. We use the energetic particle data to remotely sound the PEPs structure. From several case studies, we obtain the PEPs scale sizes and apparent velocities. We conclude that PEPs are likely the signature of the energization and entry of magnetosheath plasma into the polar magnetosphere, produced by magnetic reconnection poleward of the cusp during periods of northward-directed IMF.
