Local Magnetic Field Power Spectra from Local Data

Abstract:

Global magnetic power spectra have been used to provide insight into source depths since the inception of analytical power spectra in the 1980s. In the last two decades this concept has been expanded to local spectra obtained from global spherical-harmonic models. Recent and upcoming planetary missions such as MESSENGER, BepiColombo, and flyby missions including Galileo and Europa Clipper, however, only cover parts of a planet's surface and therefore hamper the construction of global magnetic field models. While the calculation of local power spectra from local data has been discussed in theory, no practical implementations or tests are available for realistic data sets. In this contribution we present approaches to stably invert for local power spectra and source depths from satellite data with varying altitude. We test these approaches for synthetic data of core- and crustal magnetic fields and discuss application strategies.