Geosystemics studies the Earth system as a whole, focusing on the possible coupling among the Earth layers, and using universal entropic tools. In this paper, earthquakes are considered as a long term chain of processes involving the coupling of the solid earth with the above neutral and ionized atmosphere, and finally culminating with the main rupture along the fault of concern. Some case studies are presented.

The total electron content (TEC) is being extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. The TEC presents significant changes during geomagnetic disturbed periods, causing degradation of signals in navigation systems and satellite communication. The geomagnetically disturbed periods occur due to enhanced solar activity and we show that the TEC presents intensifications not only during geomagnetic storms but also during HILDCAA events.

Ionospheric disturbances observed in Antarctica during a moderately strong geomagnetic storm caused by the impact of a coronal mass ejection from the Sun are presented here. The ionosphere behavior was analyzed using GNSS and ionosonde observations at middle and high latitudes. The results showed that the impact promptly affected the ionosphere from the Equator to the high latitudes, resulting in strong irregularities, particularly at middle and high latitudes, which can affect GPS users.

We present results of Capon's method for the estimation of in-beam images of equatorial spread F (ESF) irregularities observed by the São Luís radar interferometer. Results of numerical simulations show that, despite the short baselines of the system, the method is capable of distinguishing localized features with kilometric scale sizes (zonal direction). Results from the application of Capon’s method to actual measurements show that it is able to resolve features expected to occur in ESF.

A series of interplanetary coronal mass ejections in the period 7–17 March 2012 caused geomagnetic storms that strongly affected the high-latitude ionosphere in the Northern and Southern Hemisphere. Interhemispheric comparison of GPS phase scintillation reveals commonalities as well as asymmetries, as a consequence of the coupling between the solar wind and magnetosphere. The interhemispheric asymmetries are primarily caused by the dawn-dusk component of the interplanetary magnetic field.