Rapid geomagnetic changes inferred from Earth observations and numerical simulations

摘要

Shown are a non-reversing simulation with magnetic Reynolds number  = 386 ( , ), a reversing simulation with  = 450 ( , ) and the observational field model GGF100k ( , ). Left column shows Mollweide projections at Earth's surface of the largest change in VGP position, , as a function of location in ° yr . Red stars show the location of on each plot. Note the different colour scales and that values at each location may not have occurred at the same point in time. Right-hand panels show directional data at the locations of over a 20 kyr period with the extreme event at the midpoint. Here the top row of each panel shows the latitude of (purple), the dipole latitude (black), and the field strength (red); the bottom row shows (purple) and the rate of change of the field vector (blue). Simulations have been run for 232 kyrs for  = 386 and 415 yrs for  = 450.