HR: 0800h
AN: GP21A-0001    [Abstracts]
TI: The evolution of the core-surface flow over the last seven thousands years
AU: * Wardinski, I
EM: ingo@gfz-potsdam.de
AF: GFZ Potsdam, Sec. 2.3 Earth's Magnetic Field, GFZ Potsdam, Sec. 2.3 Earth's Magnetic Field Telegrafenberg, Potsdam, 14473 Germany
AU: Korte, M
EM: monika@gfz-potsdam.de
AF: GFZ Potsdam, Sec. 2.3 Earth's Magnetic Field, GFZ Potsdam, Sec. 2.3 Earth's Magnetic Field Telegrafenberg, Potsdam, 14473 Germany
AU: Constable, C
EM: cconstable@ucsd.edu
AF: Institue of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, Institue of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, CA 92093-0225
AB: In this study, we develop a time--dependent description of the fluid flow at the core--mantle boundary over the last seven thousands years. Magnetic diffusion should be an essential ingredient of the observed secular variation and therefore has to be considered in the inversion of the induction equation for core--surface flows. First results suggest that the core-surface flow undergoes different regimes of zonal flow direction. Epochs of a mainly westward flow alternate with epochs of a eastward flow.Also,the mean velocity of the flow seems to fluctuate. These changes in the flow direction seem to recurring periodically, with a period of about 1000 years. While the mechanism causing this variation is unassigned, it should also reflect in the length of day variation, where due to core--mantle coupling angular momentum is transfered from the core to the mantle. A comparison between the deduced length of day variation from historical eclipses and the prediction of our model is given.
DE: 1507 Core processes (1213, 8115)
DE: 1522 Paleomagnetic secular variation
DE: 1560 Time variations: secular and longer
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005