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.

In this work, we simulated the effect of atmospheric drag on satellites in low Earth orbit (LEO) during 1-month intervals of disturbed and quiet solar geomagnetic activity. Our results show that geomagnetic storms (e.g. the Bastille Day event) can cause a significant drop in LEO satellite altitudes and increase their background orbit decay rate by 50–70 %. This work can contribute to improved situational awareness and mitigation of potential threats solar energetic events pose to satellites.

The Earth's polar upper atmosphere changes along with the magnetic field, other parts of the atmosphere, and the Sun. When studying these changes, knowing the polar region that the data come from is vital, as different processes dominate the area where the aurora is and poleward of the aurora (the polar cap). The boundary between these areas is hard to find, so this study used a different boundary and figured out how they are related. Future studies can now find their polar region more easily.

Here the investigation of gravity wave (GW) properties in the low ionosphere using very low frequency (VLF) radio signals is presented. The VLF technique is a powerful tool to obtain the wave period and duration of GW events in the low ionosphere. It can be used independent of sky conditions, during daytime and year-round, which is an advantage in comparison with airglow all-sky imagers.

Ionosonde data and crustal earthquakes with magnitude M ≥ 6.0 observed in Greece during the 2003–2015 period were examined. The ionospheric anomalies are identified on the observed variations of the sporadic E-layer parameters and foF2 at the Athens observatory. The empirical relationships between ionospheric anomalies and the earthquake magnitude and the epicentral distance are obtained. The possibility of using the relationships obtained for earthquake prediction is finally discussed.