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Titel |
Interplanetary coronal mass ejections in the near-Earth solar wind during the minimum periods following solar cycles 22 and 23 |
VerfasserIn |
E. K. J. Kilpua, C. O. Lee, J. G. Luhmann, Y. Li |
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 ; 29, no. 8 ; Nr. 29, no. 8 (2011-08-30), S.1455-1467 |
Datensatznummer |
250017078
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Publikation (Nr.) |
copernicus.org/angeo-29-1455-2011.pdf |
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Zusammenfassung |
In this paper we examine the occurrence rates and properties of
interplanetary coronal mass ejections (ICMEs) and solar activity levels
during the minima following solar cycle 22 (January 1995–December 1997) and
23 (January 2007–April 2010) minima using observations from the OMNI data
base. Throughout the minimum following cycle 22 the CME and ICME rates
roughly tracked each other, while for the minimum following cycle 23 they
diverged. During the minimum after solar cycle 23, there were large
variations in the streamer belt structure. During the lowest activity period
of cycle 23 (based on sunspot numbers), the ICME rate was about four times
higher than during a similar activity period of cycle 22. We propose that
this relatively high ICME rate may be due to CME source regions occurring at
lower heliolatitudes and due to equatoward deflection of slow and weak CMEs
originating from the mid- and high-heliolatitudes. The maximum magnetic
fields of the ICMEs identified during the minimum following cycle 23 were
~30 % lower and their radial widths were ~15 % lower compared
to the ICMEs observed during the minimum following solar cycle 22. The weak
and small ICMEs may result from intrinsically weak CMEs and/or they may
represent stronger CMEs that are encountered far away from the center. |
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