Decadal and subdecadal secular variation of the Earth`s magnetic field deduced from ground based measurements and multiple satellite measurements

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We propose a detailed study of global geomagnetic secular variation on the decadal to sub-decadal scale. The first step will be an extension of a recent examination of the secular variation of the Earth's magnetic field from 1980 to 2000, which resulted in the description of two so-called geomagnetic jerks, rapid changes of secular variation, in unprecedented detail and led to the detection of other short-period variations of internal origin. Extending the model period to 1960 to 2005 will include several more geomagnetic jerks and confirm the origin of the short-period variations. We further intend to continuously model secular variation based on simultaneous measurements of more than one satellite in orbit, namely Orsted, CHAMP and SAC-C. The models derived as first step of this project will then be used for: 1) modelling of core-surface flow, 2) investigation of the spatio-temporal structure of geomagnetic jerks at the core-mantle boundary, 3) investigation of the distribution and source of short-period secular variation features. As a side-effect, we will be able to submit candidate models for the IGRF 2005 and the DGRF 2005.