HR: 0830h
AN: GP31D-0769    [PDF]
TI: The Origin of Geomagnetic Jerks, Revisited
AU: * Wardinski, I
EM: ingo@gfz-potsdam.de
AF: IPG Paris, 4, place jussieu 75252 Paris cedex 05, Paris, 75252 France
AU: Mandea, M
EM: mioara@ipgp.jussieu.fr
AF: IPG Paris, 4, place jussieu 75252 Paris cedex 05, Paris, 75252 France
AU: Holme, R
EM: r.t.holme@liv.ac.uk
AF: University of Liverpool, Dep. of Earth and Ocean Sciences Jane Herdman Lab. 4 Brownlow Street, Liverpool, L693GP United Kingdom
AB: Over the past two decades, the secular variation of the Earth's magnetic field shows rich temporal behaviour, most obviously the occurrence of magnetic jerks in 1991 and around 2000 observed at magnetic observatories at most locations on the Earth. In addition, a jerk has been identified in 1983 in data from some southern hemisphere magnetic observatories, without being seen elsewhere. This event may be associated with earlier features in the northern hemisphere. The extent, duration and the underlying processes causing these geomagnetic jerks are still debated. We developed time-dependent models for the secular variation and core surface flows for the period 1980 to 2000. These models are based on quiet monthly means and annual means of magnetic observatories and are fixed at the endpoints by satellite main field models. Our field model reveals finer temporal scale secular variation structure than previous models. In this study we also examine how well our flow models represent the characteristics of jerks, particularly those models which invoke core torsional oscillations.
DE: 1213 Earth's interior--dynamics (8115, 8120)
DE: 1507 Core processes (8115)
DE: 1560 Time variations--secular and long term
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting