Prof. Andrew Jackson | Early Earth Dynamos скачать в хорошем качестве

Prof. Andrew Jackson | Early Earth Dynamos

Speaker(s): Professor Andrew Jackson (ETH Zürich) Date: 12 September 2022 – 11:15 to 12:00 Venue: INI Seminar Room 1 Session Title: Early Earth Dynamos (Invited speaker) Event: [DY2W01] Dynamos in planets and stars - similarities and differences The Earth’s magnetic field has existed for at least 4 Gyr. Before the onset of crystallisation of the solid inner core, and for possibly as much as 90% of Earth history, the relevant geometry was that of a full sphere. Numerical studies of the geodynamo in a full sphere are thus critical for understanding the paleomagnetic field. However, direct numerical simulation of the dynamo problem in a whole sphere have been rare, partially due to the difficulty of proper treatment of the singularity at the sphere centre. Using a fully spectral method with basis functions which are smooth everywhere, we run a series of numerical simulations to investigate dynamos in a whole sphere. For various Ekman numbers E, measuring the effect of viscosity compared to the Coriolis force, the dynamo regime dependence on the Rayleigh number Ra (measuring thermal forcing) and the magnetic Prandtl number Pm (controlling electrical conductivity) was determined, and we find it to be different from that of dynamos operating in aspherical shell. With Jiawen Luo and Philippe Marti