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| Titel |
Dipole tilt effects in plasma sheet By: statistical model and extreme values |
| VerfasserIn |
A. A. Petrukovich |
| 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 ; 27, no. 3 ; Nr. 27, no. 3 (2009-03-31), S.1343-1352 |
| Datensatznummer |
250016460
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| Publikation (Nr.) |
 copernicus.org/angeo-27-1343-2009.pdf |
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| Zusammenfassung |
| With 11 years of Geotail measurements we construct a model of plasma sheet
By, depending on IMF By, coordinates X,Y and
geodipole tilt angle. At midnight and pre-midnight local times
By is positively correlated with tilt (positive in summer).
Thus in summer By is shifted towards positive values
and in winter towards negative values, so that
up to several nT could be added to the IMF influence.
The dawn side plasma sheet By generally does not exhibit any tilt
dependence, but within 15 RE the weaker negative correlation with tilt was revealed.
The tilt dependence is just a useful parametrization and several mechanisms
actually affecting plasma sheet By were previously suggested.
In particular, similar coupling between tilt and IMF By
was earlier found in the ionospheric convection patterns.
Besides this average response, extreme By (|By|>5 nT, By>IMF By) were
often observed (up to 20–25% of cases during solar maximum and in the pre-midnight
sector within 20 RE). They can not be explained by our statistical model and are
preliminary interpreted as an "over-reaction" of the magnetosphere in some
individual events. Large By field radically changes dynamics of
the current sheet and has to be taken into account during substorm-related
studies. |
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