EPS Colloquium – Jon Aurnou, UCLA

On Dynamo Action in Earth’s Basal Magma Ocean

It is argued that the early geomagnetic field must have been maintained in a relatively thin molten silicate ocean situated just above Earth’s liquid metal core. Here, we carry out detailed numerical models of such a thin layer dynamo. When coupled to models of both Earth’s thermal evolution and rotating convective turbulence, we find the electrical conductivity of the basal magma ocean (BMO) fluid is too low for dynamo action to have occurred. This finding likely requiring alternative mechanisms for generating Earth’s ancient magnetic field, a result relevant to the interpretation of ancient paleomagnetic signatures, Earth’s global-scale dynamics, and long-term planetary evolution.

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Jonathan Aurnou is Professor of Geophysics and Planetary Physics in UCLA’s Department of Earth, Planetary, and Space Sciences. He runs the Simulated Planetary Interiors Lab (SPINLab), where a mix of laboratory-theoretical studies of geophysical and astrophysical fluid dynamics are carried out. In addition, Aurnou has great interests in developing desktop STEAM systems for teaching science across all audiences via the DIYnamics Project. If the moons align, a DIYnamics kit will be brought along on this visit and desktop experiments will be carried out whenever the opportunities present themselves.