Numerical Simulations of the Geodynamo: Current Results and Future Challenges

Three-dimensional computer simulations of the geodynamo, the mechanism in the Earth’s fluid outer core that maintains the geomagnetic field, now span more than a million years, using an average computational time step of about 15 days. At the surface of the model Earth, the simulated magnetic field has an intensity, an axial dipole dominated structure, and a westward drift of the non-dipolar structure that are all similar to the Earth’s. The model’s solid inner core, being magnetically locked to the eastward fluid flow above it, rotates slightly faster than the surface of the model Earth. This computer modeling result served as a prediction for the Earth that recent seismic analyses now support. Several spontaneous reversals of the magnetic dipole polarity have also occurred during the simulations, similar to those seen in the Earth’s paleomagnetic record. However, no global convective dynamo simulation has yet been able to afford the spatial resolution required to simulate strongly turbulent convection, which surely must exist in the Earth’s low-viscosity fluid core. A series of short movies will illustrate the current results and the challenges involved in developing improved, turbulent models.

Presenter(s)

Dr. Gary A Glatzmaier received a Bachelor of Science degree, magna cum laude, from Marquette University in 1971 and then served four years as an officer in the U.S. Navy teaching nuclear reactor physics. In 1980 he received a Ph.D. in Physics from the University of Colorado. After two postdoctoral positions, he spent 16 years at the Los Alamos National Laboratory developing three dimensional time-dependent computer models to study the internal structure and dynamics of planets and stars. In 1998 he became a Professor of Earth Sciences at the University of California, Santa Cruz. In his studies of the Earth he developed separate models that simulate the global circulation and convection in the Earth's atmosphere, mantle and core. He produced computer simulations of the geodynamo, the mechanism in the Earth's fluid outer core that maintains the geomagnetic field. He has been an associate editor of the Geophysical and Astrophysical Fluid Dynamics journal since 1990 and has served on scientific committees for the AGU, SEDI, NRC, NSF, NASA, and DOE. He is a Fellow of the Los Alamos National Laboratory and of the American Geophysical Union and in 1996 won IEEE Sydney Fernbach Award for his geodynamo simulations. From 2000 - 2003 he served as the Director of the Center for the Origin, Dynamics and Evolution of Planets at UC Santa Cruz.