Time Structure of the 1991 Magnetic Jerk in the Core-Mantle Boundary Zone by Inverting Global Magnetic Data Supported by Satellite Measurements

New global magnetic data - Gauss coefficients up to degree and order 5, monthly values from 1980 to 2000, fitted to global data and partly based on high-quality satellite vector data of Magsat and CHAMP/ORSTED - are processed with a recent non-harmonic downward continuation method (Ballani et al. 2002). Using a weakly conducting mantle and the highly conducting fluid in the outer core we investigate the temporal structure of the 1991 jerk below some geomagnetic stations calculating the component dY/dt at the core-mantle boundary and underneath in different depths of the fluid outer core assuming fluid velocity there. The jerk structure dissolves and differs considerably in magnitude and in phase from the harmonically downward continued component.