Few areas of geophysics are today progressing as rapidly as basic geomagnetism, which
seeks to understand the origin of the Earth's magnetism. Data about the present …

Evidence of fast variations in the Earth's core field are seen both in magnetic observatory
and satellite records. We present here how they have been identified at the Earth's surface …

Geomagnetic jerks are abrupt changes in the second time derivative—the secular
acceleration—of Earth's magnetic field that punctuate ground observatory records. As their …

Variations in Earth's rotation (defined in terms of length of day) arise from external tidal
torques, or from an exchange of angular momentum between the solid Earth and its fluid …

The geomagnetic secular acceleration (SA), defined as the second‐order time derivative of
the Earth's core magnetic field, is investigated using data from the CHAMP satellite. We …

Data from the first year of ESA's Swarm constellation mission are used to derive the Swarm
Initial Field Model (SIFM), a new model of the Earth's magnetic field and its time variation. In …

We make use of recent geodynamo simulations to propose a reduced stochastic model of
the dynamics at the surface of Earth's core. On decadal and longer periods, this model …

Observation of the variations in the Earth's rotation at time scales ranging from subdiurnal to
multidecadal allows us to learn about its deep interior structure. We review all three types of …

Geomagnetic observations from satellites have highlighted interannual variations in the rate
of change of the magnetic field originating from Earth's core. Downward continued to the …

Continuous satellite measurements of the Earth's magnetic field have advanced the
characterization of spatial‐temporal variations of the main field over the past two decades …