Peter L. Olson

The 2011 Petrus Peregrinus Medal is awarded to Peter L. Olson for his insightful contributions to our understanding of the core mantle interactions by combining theory, numerical models and laboratory fluid dynamics model.

Peter L. Olson has combined theory, numerical models, and laboratory fluid dynamics models to interpret global geophysical data pertaining to the Earth’s deep interior. Lately he has concentrated on the dynamics of the Earth’s core, particularly the magnetohydrodynamic processes by which the geomagnetic field is generated in the fluid outer core and modified by the solid inner core and the lower mantle. His contributions to understanding the geodynamo, and in particular dipole reversals, have been a major focus in his career. He has collaborated with many colleagues in the geodynamo community. Olson has an international reputation for being an outstanding scientist. Using a combination of numerical dynamo simulations, laboratory experiments in rotating containers and the analysis of geomagnetic data, Peter has been one of the key persons who advanced our understanding of how the geomagnetic field is generated in the Earth’s liquid core and how this process is influenced by the Earth’s mantle. In his work he has addressed a broad range of topics. Following on the breakthrough in geodynamo modelling in the mid-1990s, he published an influential paper that demonstrated how the magnetic field in such models is generated by a so-called ?2-mechanism associated with helical convection columns, confirming and extending earlier concepts of Fritz Busse. The heterogeneous temperature distribution in the lower mantle imposes a laterally variable heat flow on the outer boundary of the core and Peter has used dynamo models to show that this can explain non-axisymmetric structures in the time-average palaeofield. Building on earlier and not entirely conclusive modelling attempts, he just recently clarified in a statistically robust way how heterogeneous core-mantle boundary heat flux affects the frequency of geomagnetic reversals. Together with colleagues he has published two widely recognized papers that explain possible connections between the formation of (super-) plumes in the mantle and changes in reversal rate. Motivated by results of dynamo simulations and laboratory experiments, he demonstrated that there is evidence in the recent geomagnetic field of a clockwise vortex motion at the top of the core in the North polar cap region, which was subsequently confirmed by new magnetic satellite missions a few years later. He has written important book chapters and has been very active in outreach activities (doctoral programs, summer schools..). Peter Olson is a fellow of the American Geophysical Union and the American Academy of Arts and Sciences. He is a member of the US National Academy of Science.