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| Titel |
Two-point observations of solar wind beam deceleration upstream the Earth bow shock |
| VerfasserIn |
Jaroslav Urbar, Zdenek Nemecek, Jana Safrankova, Lubomir Prech, Karel Jelinek |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106788
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| Publikation (Nr.) |
 EGU/EGU2015-9946.pdf |
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| Zusammenfassung |
| The ion energy distribution in front of the bow shock is often strongly non-Maxwellian. It can
contain a large portion (up to 10Â%) of energetic particles streaming in different directions
than the original solar wind beam. The solar wind speed is thus computed as weighted
averages of the speeds of all populations covered by the measured distribution. The moments
computed from this distribution indicate a decrease of the solar wind speed in such cases and,
based on these moments, the solar wind deceleration upstream the bow shock was
reported. Nevertheless, we have found that there are cases, when the solar wind beam
itself is undoubtedly decelerated in the foreshock region. In the present paper, we
demonstrate several examples of two-point observations of closely-separated THEMIS
spacecraft in front of the bow shock. One spacecraft is located in the solar wind while
the other is in the foreshock and observes also reflected and accelerated particles.
The speed computed as the moment of the distribution is lower than that in the
solar wind but the separation of the solar wind beam reveals its deceleration as
well. The paper discusses possible physical processes leading to this deceleration. |
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