Publications

Geomagnetic impulses ('jerks') were discovered at first in one field quantity: the dY/dt secular variation component. Because of the integral 3-D character of the field, every episodic process affects all the three field components, however often in a different way. Thus, for a comprehensive description of such processes, which give important hints for the investigation of the core-mantle boundary region, all field components should be checked commonly. We analyse several global data sets within the time span 1980-2000 with respect to the occurence of geomagnetic impulses (around the year 1991) in the single components. We study their mutual correlations, and try to clarify its common (vecorial) structure at the earth surface. Utilising these findings and assuming a mantle conductivity model (radially dependent, weak conducting and bordered by a high-conductive base layer) in a second step, we apply the nonharmonic downward continuation method to track and to analyse the distribution of geomagnetic impulses for all single field components at the CMB where they appear at an earlier stage as seen at the earth surface. Subsequently, we merge the different components for a synoptical vectorial view of the impulses found. The results of these determinations, which include the effect of a conducting mantle for the first time, mark only an initial step. Further decompositions of the space-time behavior of the vectorial impulse will be necessary to understand in more detail the physical mechanism behind.

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Ballani, L.; Greiner-Mai, H.; Stromeyer, D.; Wardinski, I.; Hagedoorn, J.; Chambodut, A. (2007): 3-D geomagnetic impulses: Synopsis of field components at the CMB.. 24th IUGG 2007 (Perugia, Italy, 2007).