Timing mirror structures observed by Cluster with a magnetosheath flow model
The evolution of structures associated with mirror modes during their flow in the Earth's magnetosheath is studied. The fact that the related magnetic fluctuations can take distinct shapes, from deep holes to high peaks, has been assessed in previous works on the observational, modeling and...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2011-10-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/29/1849/2011/angeo-29-1849-2011.pdf |
| _version_ | 1818853860428480512 |
|---|---|
| author | V. Génot L. Broussillou E. Budnik P. Hellinger P. Hellinger P. M. Trávníček P. M. Trávníček P. M. Trávníček E. Lucek I. Dandouras |
| author_facet | V. Génot L. Broussillou E. Budnik P. Hellinger P. Hellinger P. M. Trávníček P. M. Trávníček P. M. Trávníček E. Lucek I. Dandouras |
| author_sort | V. Génot |
| collection | DOAJ |
| description | The evolution of structures associated with mirror modes during their flow in
the Earth's magnetosheath is studied. The fact that the related magnetic
fluctuations can take distinct shapes, from deep holes to high peaks, has
been assessed in previous works on the observational, modeling and numerical
points of view. In this paper we present an analytical model for the flow
lines and velocity magnitude inside the magnetosheath. This model is used to
interpret almost 10 years of Cluster observations of mirror structures: by
back tracking each isolated observation to the shock, the "age", or flow
time, of these structures is determined together with the geometry of the
shock. Using this flow time the evolutionary path of the structures may be
studied with respect to different quantities: the distance to mirror
threshold, the amplitude of mirror fluctuations and the skewness of the
magnetic amplitude distribution as a marker of the shape of the structures.
These behaviours are confronted to numerical simulations which confirm the
dynamical perspective gained from the association of the statistical analysis
and the analytical model: magnetic peaks are mostly formed just behind the
shock and are quickly overwhelmed by magnetic holes as the plasma conditions
get more mirror stable. The amplitude of the fluctuations are found to
saturate before the skewness vanishes, i.e. when both structures
quantitatively balance each other, which typically occurs after a flow time
of 100–200 s in the Earth's magnetosheath. Comparison with other astrophysical
contexts is discussed. |
| first_indexed | 2024-12-19T07:43:31Z |
| format | Article |
| id | doaj.art-3ac270b692904143a2299ac7e7be359f |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-19T07:43:31Z |
| publishDate | 2011-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-3ac270b692904143a2299ac7e7be359f2022-12-21T20:30:23ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762011-10-01291849186010.5194/angeo-29-1849-2011Timing mirror structures observed by Cluster with a magnetosheath flow modelV. Génot0L. Broussillou1E. Budnik2P. Hellinger3P. Hellinger4P. M. Trávníček5P. M. Trávníček6P. M. Trávníček7E. Lucek8I. Dandouras9IRAP, UMR5277, CNRS – Université de Toulouse (UPS), Toulouse, FranceIRAP, UMR5277, CNRS – Université de Toulouse (UPS), Toulouse, FranceNoveltis, 2 Avenue de l'Europe, 31520 Ramonville Saint-Agne, FranceAstronomical Institute, ASCR, Prague, Czech RepublicInstitute of Atmospheric Physics, Prague, Czech RepublicAstronomical Institute, ASCR, Prague, Czech RepublicInstitute of Atmospheric Physics, Prague, Czech RepublicSpace Sciences Laboratory, University of California Berkeley, CA, USASpace and Atmospheric Physics Group, Blackett Laboratory, Imperial College, London, UKIRAP, UMR5277, CNRS – Université de Toulouse (UPS), Toulouse, FranceThe evolution of structures associated with mirror modes during their flow in the Earth's magnetosheath is studied. The fact that the related magnetic fluctuations can take distinct shapes, from deep holes to high peaks, has been assessed in previous works on the observational, modeling and numerical points of view. In this paper we present an analytical model for the flow lines and velocity magnitude inside the magnetosheath. This model is used to interpret almost 10 years of Cluster observations of mirror structures: by back tracking each isolated observation to the shock, the "age", or flow time, of these structures is determined together with the geometry of the shock. Using this flow time the evolutionary path of the structures may be studied with respect to different quantities: the distance to mirror threshold, the amplitude of mirror fluctuations and the skewness of the magnetic amplitude distribution as a marker of the shape of the structures. These behaviours are confronted to numerical simulations which confirm the dynamical perspective gained from the association of the statistical analysis and the analytical model: magnetic peaks are mostly formed just behind the shock and are quickly overwhelmed by magnetic holes as the plasma conditions get more mirror stable. The amplitude of the fluctuations are found to saturate before the skewness vanishes, i.e. when both structures quantitatively balance each other, which typically occurs after a flow time of 100–200 s in the Earth's magnetosheath. Comparison with other astrophysical contexts is discussed.https://www.ann-geophys.net/29/1849/2011/angeo-29-1849-2011.pdf |
| spellingShingle | V. Génot L. Broussillou E. Budnik P. Hellinger P. Hellinger P. M. Trávníček P. M. Trávníček P. M. Trávníček E. Lucek I. Dandouras Timing mirror structures observed by Cluster with a magnetosheath flow model Annales Geophysicae |
| title | Timing mirror structures observed by Cluster with a magnetosheath flow model |
| title_full | Timing mirror structures observed by Cluster with a magnetosheath flow model |
| title_fullStr | Timing mirror structures observed by Cluster with a magnetosheath flow model |
| title_full_unstemmed | Timing mirror structures observed by Cluster with a magnetosheath flow model |
| title_short | Timing mirror structures observed by Cluster with a magnetosheath flow model |
| title_sort | timing mirror structures observed by cluster with a magnetosheath flow model |
| url | https://www.ann-geophys.net/29/1849/2011/angeo-29-1849-2011.pdf |
| work_keys_str_mv | AT vgenot timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT lbroussillou timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT ebudnik timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT phellinger timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT phellinger timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT pmtravnicek timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT pmtravnicek timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT pmtravnicek timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT elucek timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel AT idandouras timingmirrorstructuresobservedbyclusterwithamagnetosheathflowmodel |