Satellite observations of energetic heavy ions during a geomagnetic storm

Abstract

Large fluxes of energetic heavy ions (M / q ≈ 16) were observed in the inner magnetosphere during the geomagnetic storm of December 17, 1971. The observations were made by a set of energetic‐ion mass spectrometers covering the energy range 0.7–12 kev on board the polar‐orbiting satellite 1971‐089A (800‐km altitude, ≈0300 LT). Significant heavy‐ion fluxes were observed for a period of approximately 48 hours during the main phase of the storm. The heavy‐ion fluxes frequently exceeded the proton fluxes in the 0.7‐ to 12‐kev energy range. The heavy‐ion spectrums were highly variable and frequently contained a peak of several kev. The heavy ions were observed over a wide latitudinal range (2.4 ≲ L ≲ 9) and generally extended to somewhat lower latitudes than the protons. The peak energy flux of these ions was approximately 0.4 erg/cm² sec ster, which is substantial in terms of expected observable ionospheric effects. They may also contribute significantly to the storm‐time magnetic‐field depression (Dst), since at the same flux they represent an energy density greater by a factor of 4 than that of the protons.

Motions of Charged Particles in the Magnetosphere Under the Influence of a Time-Varying Large Scale Convection Electric Field

“…The discoveries of ions in the magnetosphere heavier than hydrogen (Shelley et al, 1972) and ion and electron beams directed up along magnetic field lines from the atmosphere Johnson et al, 1977;McIlwain_, 1975) have suggested that the ionosphere may he a source for ring current particles, rather than, or in addition to, the plasma sheet.…”

Space Storms and Space Weather Hazards

“…Although some of the early measurements by mass spectrometers in space discovered energetic heavy ions of ionospheric origin (e.g., Shelley et al, 1972;Balsiger et al, 1980), it was relatively recently that the role of ionospheric particles in the ring current evolution during storms became evident after the AMPTE mission (Krimigis et al, 1982). The AMPTE lifetime coincided with the solar minimum, and thus only one great storm was observed.…”

“…In the early 1970s the solar-origin paradigm was challenged by the discovery of energetic heavy ions (i.e., ions with M/q=16) at energies up to 17 keV (Shelley et al, 1972) by the first mass spectrometer in space, on board the polar-orbiting satellite 1971-089A. These ions were presumably O + ions originating in the terrestrial ionosphere.…”

“…Influence of the terrestrial atmosphere on space storm dynamics Space-atmosphere coupling was revealed by the first oxygen measurements of the polar-orbiting satellite 1971-089A (Shelley et al, 1972). The importance of terrestrial matter in dynamical space processes has been progressively recognized, through both observational and theoretical studies (e.g., Baker et al, 1982;Moore and Delcourt, 1985;Daglis et al, 1991;Cladis and Francis, 1992;Rothwell et al, 1995;Lakhina and Tsurutani, 1997;Daglis, 1997a,b;Silevitch et al, 2000).…”

Magnetospheric and auroral plasmas: A short survey of progress

“…Recent low-altitude observations of the composition of positive ions precipitating into the auroral zone suggest that at least part of these plasmas can be attributed to the ionosphere. Shelley, Sharp and Johnson [1972] have reported the convincing discovery of large intensities of energetic oxygen ions during geomagnetic storms. A exemplary set of observations is given in Figure 10.…”