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| Titel |
Magnetic energy fluctuations on the core-mantle boundary |
| VerfasserIn |
Ludwig Ballani, Jan M. Hagedoorn, Dietrich Stromeyer, Hans Greiner-Mai |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051848
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| Zusammenfassung |
| Considering the magnetic field energy and its temporal changes on the core-mantle boundary
(CMB) has multivalent relevance: They can reflect and evaluate dynamical processes
which are modelled on the basis of surface field data. On the other hand, these
quantities form a significant link to features of the deeper field generation by a dynamo
process.
Our investigation is focused on the temporal changes of geomagnetic field energy on the
CMB and their connection with sudden trend changes of the geomagnetic secular variation
on the CMB (jerks). We show examples of the different components (radial and
tangential) at different epoches. Further, we investigate the differently influenced degree
parts. A measure for the total activity is introduced and compared for the whole
CMB.
As data we use the geomagnetic field model C3FM2 (Wardinski and Lesur, GFZ
Potsdam, 2009) covering the years 1957-2006, which enables secular variation
investigations with monthly values. Assuming a low, radially dependent mantle conductivity
with a conductance of about 107S, we determine the geomagnetic field and the
secular variation components on the CMB by the method of non-harmonic downward
continuation. With these field quantities the geomagnetic energy and its time derivative on
the CMB can be calculated. For the jerk detection, we use a simple straight-line
approximation algorithm applied to each (Ï,φ) position of a global 1 degree by 1 degree
grid. |
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