 |
| Titel |
Magnetically dominated structures as an important component of the solar wind turbulence |
| VerfasserIn |
R. Bruno, R. D'Amicis, B. Bavassano, V. Carbone, L. Sorriso-Valvo |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 25, no. 8 ; Nr. 25, no. 8 (2007-08-29), S.1913-1927 |
| Datensatznummer |
250015906
|
| Publikation (Nr.) |
 copernicus.org/angeo-25-1913-2007.pdf |
|
|
|
|
|
| Zusammenfassung |
| This study focuses on the role that magnetically dominated
fluctuations have within the solar wind MHD turbulence. It is
well known that, as the wind expands, magnetic energy starts to
dominate over kinetic energy but we lack of a statistical study
apt to estimate the relevance of these fluctuations depending on
wind speed, radial distance from the sun and heliographic
latitude. Our results suggest that this kind of fluctuations can
be interpreted as non-propagating structures, advected by the
wind during its expansion. In particular, observations performed
in the ecliptic revealed a clear radial dependence of these
magnetic structures within fast wind, but not within slow wind.
At short heliocentric distances (~0.3 AU) the turbulent
population is largely dominated by Alfvénic fluctuations
characterized by high values of normalized cross-helicity and a
remarkable level of energy equipartition. However, as the wind
expands, a new-born population, characterized by lower values of
Alfvénicity and a clear imbalance in favor of magnetic energy
becomes visible and clearly distinguishable from the Alfvénic
population largely characterized by an outward sense of
propagation. We estimate that more than 20% of all the
analyzed intervals of hourly scale within fast wind are
characterized by normalized cross-helicity close to zero and
magnetic energy largely dominating over kinetic energy. Most of
these advected magnetic structures result to be non-compressive
and might represent the crossing of the border between adjacent
flux tubes forming, as suggested in literature, the advected
background structure of the interplanetary magnetic field. On the
other hand, their features are also well fitted by the Magnetic
Field Directional Turnings paradigm as proposed in literature. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|