HR: 13:40h
AN: GP33A-01 INVITED     [Abstracts]
TI: Examining Geomagnetic Jerks Using Comprehensive Magnetic Field Models
AU: * Sabaka, T J
EM: sabaka@geomag.gsfc.nasa.gov
AF: Terence J. Sabaka, Geodynamics Branch, Code 921 Goddard Space Flight Center NASA, Greenbelt, MD 20771 United States
AU: Olsen, N
EM: nio@dsri.dk
AF: Nils Olsen, Danish Space Research Institute, Copenhagen, DK-2100 Denmark
AB: The latest comprehensive magnetic field model, CM4, spans 1960-2002, and as a result, traverses several instances of a phenomenon known as a geomagnetic jerk. These are generally accepted as worldwide events of internal origin, which have been theorized by some to be jumps in acceleration of the fluid motion at the core-mantle boundary or created by torsional oscillations in the core. They are usually manifested in the magnetic record as sudden changes in slope of otherwise linear segments in the secular variation of the field. It is speculated, however, that certain jerks may not be detected over the entire globe and may even be influenced by external signals. This is intriguing: CM4 provides not only a global description of the evolution of the field through time, but also attempts to separate the internal from the external signals, even the induced from the core, during quiet-time conditions. This suggests that the model is well suited to test such claims, and this talk will report on progress towards this end.
DE: 1507 Core processes (8115)
DE: 1515 Geomagnetic induction
DE: 1530 Rapid time variations
DE: 1560 Time variations--secular and long term
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting