Abstract
The ability to derive Gauss coefficients, up to and including degree 3, and their variation through a geomagnetic polarity transition is studied using simulated palaeomagnetic data. It is concluded that for a specified distribution of palaeomagnetic sites reasonable estimates of the behaviour of the coefficients can be derived even when uncertainties in the data, and in the compilation of contemporaneous records, are considered. Published palaeomagnetic records of the Matuyama–Brunhes transition are then used as basis for deriving the variation of the Gauss coefficients over a 32 kyear period encompassing the reversal. Individual records are interpolated to uniform time intervals of 0.5 kyear and put on to a common time scale by correlating between sites the variation in the latitude of VGP's through the reversal. Relative palaeointensity data are scaled by the geocentric axial dipole field intensity for 2000 at each site, and the Gauss coefficients derived by a matrix inversion employing singular value decomposition. The derived variation with time of the Gauss coefficients suggests that, over the time span of the data, the dipole and non-dipole fields have approximately equal intensities. Plots of the variation of the surface vertical magnetic field through the reversal suggest that immediately prior to the reversal a large patch of reverse flux appears in the southern hemisphere. This may subsequently have been responsible for the weakening of the vertical field leading into the reversal. A similar patch of reverse flux is observed some 20–15 kyear prior to the actual reversal and may be associated with an observed excursion in VGPs at several sites.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.