ISSN:
0992-7689
Keywords:
Magnetospheric physics (auroral phenomena; plasma convection)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract We examine ion flux dropouts detected by INTERBALL-Auroral upon traversal of the auroral zone at altitudes of ≈13 000 up to 20 000 km. These dropouts which we refer to as “gaps”, are frequently observed irrespectively of longitudinal sector and appear characteristic of INTERBALL-Auroral ion spectrograms. Whereas some of these gaps display a nearly monoenergetic character (≈12 keV), others occur at energies of a few hundreds of eV up to several keV. INTERBALL-Auroral data exhibit the former monoenergetic gap variety essentially in the evening sector. As examined in previous studies, these gaps appear related to transition from particle orbits that are connected with the magnetotail plasma source to closed orbits encircling the Earth. The latter gap variety, which spreads over several hundreds of eV to a few keV is often observed in the dayside magnetosphere. It is argued that such gaps are due to magnetospheric residence times well above the ion lifetime. This interpretation is supported by numerical orbit calculations which reveal extremely large (up to several tens of hours) times of flight in a limited energy range as a result of conflicting E × B and gradient-curvature drifts. The characteristic energies obtained numerically depend upon both longitude and latitude and are quite consistent with those measured in-situ.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s00585-999-0734-9
Permalink
