Spatiotemporal sampling of Sq+‐induced geomagnetic responses at LEO satellite altitude for a radially conductive Earth
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A new simulation tool is introduced for extracting Earth conductivity information from geomagnetic satellites in low Earth orbit (LEO) such as CHAMP, Swarm and potential follow-on missions. Theoretical reconstruction of spherical harmonic spectra of global universal time (UT) geomagnetic field maps is analysed. An idealized regular solar daily variation field is assumed, along with its induced counterpart from a radially stratified Earth. Solar-quiet (Sq) spectra can be reliably reconstructed from discrete time-series of measurements sampled daily within a fixed UT window. A single LEO satellite should be in orbit for at least 1 yr under quiet-time conditions to ensure accurate spectral reconstruction of an Sq geomagnetic spectrum. The length of the daily sampling window and random day-to-day variability in the Sq source strength have only minor effects on spectral reconstruction. The shape of the spectra, and spectral ratios, are independent of radial mantle conductivity. Further research employing 3-D forward modelling of induction in a laterally heterogeneous earth, with more realistic and complete external source descriptions, is advocated. The new simulation tool should prove valuable to planners of future multisatellite geomagnetic missions, as well as scientists interested in analysing and interpreting satellite induction signals. © 2010 The Author Geophysical Journal International © 2010 RAS.
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