Division I - WG 1: Theory of Planetary Magnetic Fields
WGI-1 covers all theoretical aspects concerning the origin and properties of the main magnetic fields of the Earth and planets, including the geomagnetic secular variation. Current theoretical understanding is that dynamo action of motions in the electrically conducting fluid cores of planets is the main mechanism of magnetic field generation. The magnetic field measurements of magnetic observatories and satellites, and knowledge of the structure, dynamics, physics and chemistry of planetary cores are used to constrain theories. The results from studies of palaeomagnetic and archaeomagnetic data, and of conductivity, seismic, gravitational, rotational and heat flow data provide additional observational constraints on the terrestrial magnetic field. Computational modeling, and laboratory experiments of conducting and non- conducting fluids are vital to theoretical progress.