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| Titel |
Cross-field gradients: general concept, importance of multi-spacecraft measurements and study at 1 AU of the source intensity gradient for E > 30 keV solar event electrons |
| VerfasserIn |
P. A. Chaizy |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 18, no. 3 ; Nr. 18, no. 3, S.263-276 |
| Datensatznummer |
250013930
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| Publikation (Nr.) |
 copernicus.org/angeo-18-263-2000.pdf |
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| Zusammenfassung |
Three main physical processes (and associated
properties) are currently used to describe the flux and anisotropy time profiles
of solar energetic par- ticle events, called SEP profiles. They are (1) the
particle scattering (due to magnetic waves), (2) the particle focusing (due to
the decrease of the amplitude of the interplanetary magnetic field (IMF) with
the radial distance to the Sun) and (3) the finite injection profile at the
source. If their features change from one field line to another, i.e. if there
is a cross IMF gradient (CFG), then the shape of the SEP profiles will depend,
at onset time, on the relative position of the spacecraft to the IMF and might
vary significantly on small distance scale (e.g. 106 km). One type of
CFG is studied here. It is called intensity CFG and considers variations, at the
solar surface, only of the intensity of the event. It is shown here that drops
of about two orders of magnitude over distances of ~104 km at the
Sun (1° of angular distance) can influence dramatically
the SEP profiles at 1 AU. This CFG can lead to either an under or overestimation
of both the parallel mean free path and of the injection parameters by factor up
to, at least, ~2-3 and 18, respectively. Multi-spacecraft analysis can be
used to identify CFG. Three basic requirements are proposed to identify, from
the observation, the type of the CFG being measured.
Key words: Solar physics, astrophysics, and astronomy
(energetic particles; flares and mass ejections) - Space plasma physics
(transport processes) |
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