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| Titel |
Alfvénic fluctuations in "newborn"' polar solar wind |
| VerfasserIn |
B. Bavassano, E. Pietropaolo, R. Bruno |
| 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 ; 23, no. 4 ; Nr. 23, no. 4 (2005-06-03), S.1513-1520 |
| Datensatznummer |
250015241
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| Publikation (Nr.) |
 copernicus.org/angeo-23-1513-2005.pdf |
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| Zusammenfassung |
| The 3-D structure of the solar wind is strongly dependent upon
the Sun's activity cycle. At low solar activity a bimodal structure is
dominant, with a fast and uniform flow at the high latitudes, and slow and
variable flows at low latitudes. Around solar maximum, in sharp contrast,
variable flows are observed at all latitudes. This last kind of pattern,
however, is a relatively short-lived feature, and quite soon after solar
maximum the polar wind tends to regain its role. The plasma parameter
distributions for these newborn polar flows appear very similar to those
typically observed in polar wind at low solar activity. The point addressed
here is about polar wind fluctuations. As is well known, the low-solar-activity
polar wind is characterized by a strong flow of Alfvénic fluctuations. Does
this hold for the new polar flows too? An answer to this question is given
here through a comparative statistical analysis on parameters such as total
energy, cross helicity, and residual energy, that are of general use to
describe the Alfvénic character of fluctuations. Our results indicate that
the main features of the Alfvénic fluctuations observed in
low-solar-activity polar wind have been quickly recovered in the new polar
flows developed shortly after solar maximum.
Keywords. Interplanetary physics (MHD waves and turbulence;
Sources of the solar wind) – Space plasma physics
(Turbulence) |
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