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| Titel |
Comparative views of geomagnetic jerks |
| VerfasserIn |
Ludwig Ballani, Jan M. Hagedoorn, Dietrich Stromeyer, Ingo Wardinski, Hans Greiner-Mai |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035953
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| Zusammenfassung |
| New geomagnetic field models (Wardinski and Lesur, GFZ Potsdam, 2009) covering the
years 1957–2006 - here the model C3FM2 - enable new comparative secular variation
investigations. Combined with the method of non-harmonic downward continuation and e.g.
assuming a low, radially dependent mantle conductivity with a conductance of about 107 S,
we can determine the three secular variation components also for the core-mantle
boundary.
For this time span, the jerks (which are sudden trend changes in the geomagnetic secular
variation, e.g. around the years 1969, 1978, 1991) have been studied at the earth surface
mainly by observatory data. We extend this to a common and uniform view of the jerks, both
for the earth surface and the core-mantle boundary finding their different global topologies
and their temporal characteristics. The jerk detection of a single secular variation component
is done by a simple straight-line approximation algorithm applied to each (Ï,φ)
position of a global 1° by 1° grid. For the individual jerks, we show comparatively the
time structure, i.e. the global/regional distribution of the jerk occurrence times in
dependency of the time. It is clearly specific for each single component and each jerk and
reveals also partly significant spectral differences between radial and tangential
components. |
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