Core field accelerations from Swarm and ground observatory data

Abstract:

On sub-decadal timescales the evolution of Earth's core-generated magnetic field is characterized by localized acceleration events, including oscillations. Our observational knowledge of these features, which are an important signature of the dynamics taking place within the core, is however still at a rudimentary stage. In this contribution we describe how observations from the Swarm multi-satellite mission, combined with data from ground observatories, can now be used to study the most recent field accelerations. An updated version of the CHAOS time-dependent geomagnetic field model will be presented, with a focus on details of the selection and incorporation of Swarm data including field gradient estimates. Comparisons between field accelerations observed by Swarm and at ground observatories will be presented. Implications for the strengthening and weakening of the field at specific locations at Earth's surface will be described. Finally, we will discuss the resolution of acceleration events at the core surface and possible underlying core flows.