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Simulated reversal of the magnetic field of the Earth, caused by variations in the radial profile of the alpha-effect. The toroidal magnetic field is on the left, the poloidal-field vectors are on the right.
Graph: A. Giesecke
[web size] [full size]
more at /highlight_archive/giesecke2/index.html (image added 2006-01-31) |
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Time series for simulated reversals of the magnetic field of the Earth. The value plotted is the radial magnetic field at the north pole. A total of 173 reversals has been identified. The polarity life-time is about 11 diffusion times.
Graph: A. Giesecke
[web size] [full size]
more at /highlight_archive/giesecke2/index.html (image added 2006-01-31) |
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Radial profiles of the alpha-effect, for which a spherical alpha^2 mean-field dynamo yields oscillating solutions. The profile has to be within the grey channel to produce oscillations.
Graph: A. Giesecke
[web size] [full size]
more at /highlight_archive/giesecke2/index.html (image added 2006-01-31) |
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Radial profiles of the alpha-effect, for which a spherical alpha^2 mean-field dynamo yields oscillating solutions. The profile has to be within the grey channel to produce oscillations.
Graph: A. Giesecke
[web size] [full size]
more at /highlight_archive/giesecke2/index.html (image added 2006-01-31) |
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The convection in the outer core of the Earth can lead to irregular magnetic field reversals. This is simulated by a statistically fluctuating zero of the alpha-effect in a full-sphere computation. The left panel shows the 'active' shell corresponding to the yellow-lilac area above, but now showing the strength of the magnetic field. The upper right panel gives the fluctuation of the ?-distribution. The dashed lines indicate the very narrow channel in which oscillatory solutions can occur. The lower right panel measures the magnetic field at the north pole. The polarity is constant over long periods of time, but occasionally it is changed. (MPEG, 16MB)
Simulation and graphics: A. Giesecke
more at http://www.aip.de/highlight_archive/giesecke2/ (image added 2005-02-22) |
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Prozentsatz der ausgestorbenen Arten pro Zeitintervall im Verlauf der letzten 260 Millionen Jahre der Erdgeschichte. Das größte Artensterben ist mit dem Sauriersterben vor 65 Millionen Jahren verbunden.
Grafik nach Andreas von Rétyi
[web size] [full size](image added 2004-11-11) |
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