Inter-annual waves in the Earth’s core and their imprint in geomagnetic observations

In recent decades satellite observations have revealed geomagnetic field variations on a global scale at inter-annual periods. Some of these variations appear to be periodic, suggesting a wave-like mechanism as an underlying physical mechanism within the Earth’s core. Through the analysis of flows, inverted from geomagnetic data, we have previously isolated oscillating wave motions at the surface of the core that are in large agreement with quasi-geostrophic Magneto-Coriolis (QGMC) waves. The sensitivity of these QGMC waves to a steady magnetic field within the Earth’s core is investigated and put into context with previous theoretical/numerical considerations as well as some of the observational constraints available.

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