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| Titel |
Importance of the magnetic field cone angle in magnetic clouds |
| VerfasserIn |
Lucile Turc, Philippe Escoubet, Dominique Fontaine, Emilia Kilpua |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126390
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| Publikation (Nr.) |
 EGU/EGU2016-6101.pdf |
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| Zusammenfassung |
| The properties of magnetic clouds (MCs) observed by either ACE or Wind in L1 from 2000
to 2014 are investigated. The results obtained for their basic properties, such as the average
density, velocity and magnetic field intensity, are consistent with previous studies.
We then focus on the orientation of the magnetic field inside MCs. We find that
in most cases the direction of the MCs’ magnetic field departs from that of the
Parker-spiral interplanetary magnetic field usually encountered during quiet times. As a
consequence, the position of the quasi-parallel and quasi-perpendicular regions of
the Earth’s bow shock will differ from the textbook picture (quasi-parallel on the
dawnside, quasi-perpendicular on the duskside). The distribution of the different
shock geometries along the shock’s surface can have a strong impact on the solar
wind-magnetospheric coupling (e.g. asymmetries in the magnetosheath, modification of the
MCs’ magnetic structure...). Using events during which observations inside the
magnetosheath are available and with the help of a magnetosheath model, we obtain an
estimate of the ΘBn angle, between the shock normal and the upstream magnetic field,
encountered upon entering the magnetosheath. We show that for a given cone angle,
the magnetosheath observations are associated with only a limited range of ΘBn
values. Therefore, it appears that the cone angle gives a good approximation of the
encountered shock configuration. In the context of space weather forecasting, we
discuss the importance of predicting not only the Bz component of the magnetic field
inside MCs, but also the other components and in particular the Bx component, as
they affect the position of the quasi-parallel and quasi-perpendicular regions of the
terrestrial bow shock, which in turn influences the driving of the magnetosphere. |
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