Magnetic field coupling across the Earth system as screened by the ionosphere

From its core to the magnetosphere and further into the solar wind, the Earth system is tightly coupled and the magnetic field is the glue that mediates the coupling. At the same time, the ionosphere behaves as a huge natural screen, where phenomena from above and below provide a broad range of complicated signatures, mapped along the magnetic field. The proper reading and disentangling of these signatures have a major potential to advance the fundamental understanding of the coupled Earth ‘spheres’ as well as of a vast set of applications and tools, covering from space weather and natural hazards to effects on space-borne and ground-based technology. While this is in principle well understood, the actual handling of the ionospheric observations and the tracing of the true sources behind ionospheric disturbances is often most challenging. The presentation will illustrate a few examples, emphasizing the major importance of the magnetic field in providing the coupling, of the ionosphere in screening it, and of a systematic approach yet to be done.