At times when auroras erupt on the sky, the magnetic field surrounding the Earth undergoes rapid changes. On the ground, these changes can induce harmful electric currents in technological conductor networks, such as powerlines. We have used magnetic field observations from northern Europe during 28 such events and found consistent behavior that can help to understand, and thus predict, the processes that drive auroras and geomagnetically induced currents.

Global Positioning System (GPS) measurements of plasmasphere electron content (PEC) by Jason-2 are compared to PEC for ground-based GPS receivers in Africa. Jason-2 vertical PEC measurements corroborated the ground-based measurements, and its co-aligned slant PEC values were generally close to the ground-based slant PEC values. This correspondence indicates that the Jason-2 PEC measurements could be used to resolve some ambiguities in the determination of the ground-based PEC values.

The solar wind interaction with Earth’s magnetic field deposits energy into the upper portion of the atmosphere at high latitudes. The coupling process that modulates the ionospheric convection and intensity of ionospheric currents leads to formation of densely ionized patches convecting across the polar cap. The ionospheric currents launch traveling ionospheric disturbances (TIDs) propagating equatorward. The polar cap patches and TIDs are then observed by networks of radars and GPS receivers.

Using the Digisonde data this paper shows that the small variation in the geomagnetic activity during low solar activity can affect both the parameter of height and the frequency of the intermediate layer (ILs) over the low-latitude Brazilian sector. The most expressive responses of the ILs to geomagnetic activity were observed during the summer when the height of the ILs suffered a significant decrease with the increase of the magnetic activity magnetic in the first hours of the day.

The paper discusses the excitation of monochromatic ELF/VLF electromagnetic waves produced by HF heating facility currents in the nighttime ionosphere. The ground-based magnetic field is predominantly located under the source, and the wave has right-hand polarization typical for a whistler but left-hand polarization at large distances from the source. About half of the source energy propagates upward, and approximately 20 % propagates to the Earth–ionosphere waveguide.