5:15 PM - 6:30 PM
[SEM34-P12] The empirical mode analysis of the decadal variations in the geomagnetic Gauss coefficients
Keywords:geomagnetic decadal variations, Gauss coefficients, outer core, torsional oscillations, empirical mode decomposition
We use the time series of the last 150 years of the Gauss coefficients with degrees up to 4, from 1865 to 2014. We combine the data from gufm1 model (Jackson, 2000), IGRF-12 and CHAOS-5 model (Finlay, 2015), and apply the empirical mode decomposition (EMD) (Huang et al., 1998) to time series of the Gauss coefficients.
The decomposition shows that the equatorial antisymmetric components of Gauss coefficients have periods of 40 and 80 years. The g-h plots of these components show linearly polarized oscillations, which indicate either forced oscillations, or advection by oscillating flows.
Next we subtract the components which can be caused by advection by axisymmetric flows. The results will be shown at the conference.