HR: 10:20h
AN: SM51E-01    [PDF]
TI: SAMPEX Observations of the Inner Radiation Belt Over a Complete Solar Cycle
AU: * Looper, M D
EM: mark.d.looper@aero.org
AF: The Aerospace Corporation, Mail Station M2/260 P.O. Box 92957, Los Angeles, CA 90009-2957
AU: Blake, J B
EM: jbernard.blake@aero.org
AF: The Aerospace Corporation, Mail Station M2/260 P.O. Box 92957, Los Angeles, CA 90009-2957
AU: Mewaldt, R A
EM: rmewaldt@srl.caltech.edu
AF: Space Radiation Laboratory, 220-47 Caltech, Pasadena, CA 91125 United States
AB: The Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite was launched into low Earth orbit in July 1992, and has been measuring energetic protons and heavy hydrogen isotopes during several traversals of the inner radiation belt each day since then. We have now accumulated a data set covering a full 11-year cycle of solar activity (from declining phase of Cycle 22 to the declining phase of the current Cycle 23), and have assembled it into time-varying maps of several parameters of the radiation belt. We will describe the variations of energy spectra, pitch-angle distributions, scale height, and isotopic composition as the solar activity level changed during the mission. The scale height (measured through gradient anisotropy, the "East-West effect") at the lower edge of the radiation belt responds to changes in the upper atmosphere over the solar cycle. Varying isotopic composition, especially considering the 12-year half-life of tritium, reflects the differing sources and losses for the CRAND protons and secondary deuterium and tritium. Time variations at the upper edge of the radiation belt at energies of tens of MeV respond to geomagnetic injections of these high-energy particles as well as to the relatively steady CRAND source and atmospheric losses. This data set is being incorporated into models of the low-altitude inner zone that seek to improve on the two-state (solar max, solar min) AP8 model by including continuous response to changes in solar activity.
DE: 2162 Solar cycle variations (7536)
DE: 2720 Energetic particles, trapped
DE: 2730 Magnetosphere--inner
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting