The Origin of Magnetic Fields in Terrestrial Planets
Magnetic fields are generated by fluid motion in the liquid metal cores of terrestrial planets. While numerical models offer valuable insights into the process, many of the details are still poorly understood because the models operate at conditions that are very far from the planetary setting. Historical observations on Earth cover a time interval too short to provide much help, so we turn to geological observations to understand the origin of the dipole field. The geological observations suggest that dipole trends are asymmetric in time. Increases in the dipole field are more rapid on average and occur less frequently than decreases in the field over timescales of several tens of thousands of years. This behavior is compatible with a field-generation mechanism that departs from standard arguments. Numerical models partially support the modified generation mechanism, although the level of asymmetry in the models is much weaker than that suggested by the geological observations. Speculations about future improvements in the numerical models suggest a convergence of models and observations as more realistic conditions are achieved.
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About the SpeakerI was an undergraduate at the University of Toronto and completed my PhD in Geophysics at Harvard (with astronomer Irwin Shapiro as my advisor). I spent two years as a postdoc with Herbert Huppert at the Institute of Theoretical Geophysics, which was then part of DAMTP at the University of Cambridge. My first faculty position was in the Department of Geophysics and Astronomy at the University of British Columbia. I moved to the Department of Geophysical Sciences at the University of Chicago and later moved to UC Berkeley in the Department of Earth and Planetary Science.
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