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Abstract

The main geomagnetic field originates in Earth’s outer core and shields our habitat against solar wind and cosmic radiation. Global descriptions of the field evolution are provided by data-based models. Such models are available for time spans from a few years to the past 100 kyr and some geomagnetic field polarity excursions and reversals. They are useful tools for several scientific and practical purposes. Recent models are based on high precision absolute measurements of the geomagnetic field by satellites and ground observatories. A remaining challenge for them is to accurately separate the various field contributions, that include signals from magnetized rocks and geological structures in Earth’s lithosphere, and from electric currents flowing outside the Earth in the ionosphere and magnetosphere. Further back in time, models rely on historical observations, archeo– and paleomagnetic data. The resolution of these models in both space and time is limited compared to the present day. The main challenges for these models are inherent uncertainties in the recorded magnetic signal and the dating of the recording material, and sparse data coverage. Nevertheless, they provide an improved picture of the geomagnetic field evolution over geological times. This review paper gives a brief overview of the latest developments in geomagnetic field modelling on several time-scales.