HR: 13:40h
AN: GP23A-01    [Abstracts]
TI: Magnetic Dipole Reversals in Dynamo Simulations
AU: * Glatzmaier, G A
EM: glatz@es.ucsc.edu
AF: University of California, Earth and Planetary Sciences Department, Santa Cruz, CA 95064, United States
AU: Coe, R S
EM: rcoe@es.usc.edu
AF: University of California, Earth and Planetary Sciences Department, Santa Cruz, CA 95064, United States
AU: Roberts, P H
EM: roberts@math.ucla.edu
AF: University of California, Institute of Geophysics and Planetary Physics, Los Angeles, CA 90095, United States
AU: Olson, P L
EM: olson@jhu.edu
AF: Johns Hopkins University, Department of Earth and Planetary Sciences, Baltimore, MD 21218, United States
AB: Although 3D MHD simulations of convective dynamos continue to improve as computers become faster and resources become more available, we are still far from being able to produce a realistic geodynamo simulation in terms of the input parameters. Modelers are compelled to choose between as much spatial and temporal resolution that is currently practical in order to reach smaller Ekman numbers and more turbulent (i.e., realistic) dynamics or to use very coarse resolution and less Earth-like parameters in order to simulate enough time to study reversals. Here we present results from the latter approach. We use the Glatzmaier-Roberts anelastic model with a finitely conducting inner core that is free to rotate. The Ekman number, ν/(2 Ømega D²), is set to 5 × 10^-4. Here, ν is the viscous diffusivity, Ømega is the angular velocity and D is the depth of the fluid outer core. We set the magnetic diffusivity to 2 m²/s and the other three to 20 m²/s. No hyperdiffusion is employed. With the correct core size, this Ekman number requires the rotation rate to be 20,000 times smaller than the Earth's. The coarse resolution (66x72x144) produces large-scale laminar flows and fields. Magnetic reversals do occur, although the vast difference between model and Earth parameters complicates their interpretation.
DE: 0560 Numerical solutions (4255)
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1507 Core processes (1213, 8115)
DE: 1510 Dynamo: theories and simulations
DE: 1535 Reversals: process, timescale, magnetostratigraphy
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting