New high temporal and spatial resolution measurements by SAMPEX of the precipitation of relativistic electrons

• Published in: Advances in space research 1996, Vol.18 (8), p.171-186
• Main Authors: Blake, J.B, Looper, M.D, Baker, D.N, Nakamura, R, Klecker, B, Hovestadt, D
• Format: Article
• Language: English
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/0273-1177(95)00969-8

The precipitation of electrons of 150 keV and 1 MeV in the outer zone have been measured by an instrument aboard the low-altitude, polar-orbiting SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer)satellite. This instrument has an extremely large geometric factor (100 cm 2 sr at 1 MeV) and is sampled ten times per second. Broad areas of strong precipitation, extending ∼ 2–3° in latitude, frequently are observed near the high-latitude boundary of the outer zone. These features can persist for hours and are seen in conjugate locations. A transient form of strong precipitation, a microburst, is also seen regularly. Microbursts often are seen lasting for less than a second, indicating that microbursts sometimes occur in a very localized region; the narrow temporal structure is a consequence of the orbital velocity of SAMPEX. In other cases, where the spatial size is greater, the temporal evolution of the microburst can be followed. These sum of these observations clearly indicates that outer-zone electron precipitation frequently results from a strong scattering process, and not by weak diffusion of stably trapped electrons into the drift loss cone.