ALBERT

Description: Investigating the dynamics of liquid iron at the top of the core requires an inversion process from magnetic field measurements. Due to possible leakage, traditional spectral techniques are not optimal for regional investigations or studies of Secular Variation (first time derivative of magnetic field, SV) on short-time periods. Improved data coverage and quality from satellite missions have provided insight into short-period dynamics (such as jerks and waves), and improved understanding of localised features. However, there continues to be a need for new techniques for better spatio-temporal models of flow motions at the top of the core, especially for regional investigations. The aim of this work is to investigate regional dynamics at the Core-Mantle Boundary (CMB) using the SOLA (Subtractive Optimally Localised Averages) methodology. This method allows us to create point estimates of radial field SV at the CMB by considering global satellite measurements. The SOLA methodology allows for a local estimate of radial field SV at any desired location directly at the CMB, which opens the way to investigations of regional dynamics. Producing localised-average estimates at the CMB bypasses many problems encountered when using only a subset of magnetic satellite data, downward continuing data, and models based on spherical harmonics. Finally, we discuss how the SOLA methodology can be incorporated into the PyGeodyn code to produce core flow models. This approach can provide additional information on wave-like flow motions at the top of the Earth’s core where these are most prominent, and permits new investigations of shorter period phenomenon.