The real time monitor and prediction of solar-terrestrial processes is increasing importance in our society, because of its dependence on advanced technology that relies on continuous power availability, radio wave communication and navigation, and satellite operation. Enhanced solar wind and solar radiation input energy into near-Earth space result, for example, in strong electric currents flowing in the magnetosphere and ionosphere, and in significant plasma density structuring or alterations of neutral composition, density and winds in the upper atmosphere (e.g., Tsurutani et al., 1997; Prolss, 2011; Piersanti 2017). Such periods of enhanced activity are often called magnetic storms since they cause rapid variations of the geomagnetic field of up to several hundred nanotesla within a few minutes. Strong variations of ionospheric currents, such as the auroral electrojet, cause induced electric fields in the conducting solid Earth that may harm power grid systems (e.g. Kappmenman, 1989; Thomson, 2007; Carter et al., 2017; Piersanti et al., 2018). Variations in the strength and direction of the geomagnetic field, that are caused by both the polar electrojets and the magnetospheric ring current can disturb navigation activities that are based on precise magnetic maps, e.g., for aviation or exploration directional drilling activities. Steep plasma density gradients in the ionosphere and plasmasphere bend and scatter trans-ionospheric radio waves that are used for satellite-based navigation (i.e. the Global Positioning System – GPS - and the Galileo). Such irregularities result in navigational errors that are not included in ionospheric correction models implemented in commercial GPS receivers and may lead to signal outage and radio wave scintillations (e.g., Basu et al., 2002). Scintillations, such as equatorial F region plasma irregularities, also have to be considered as regular disturbances, that are independent of magnetic storm activity. Irregular thermospheric density enhancements also have significant effects on satellite drag and space debris monitoring.
Observations from the CSES satellite mission have large value for near Earth space research. The mission, equipped with high precision instruments, carries simultaneous measurements of the magnetic, electric, plasma and neutral environment in near-Earth space. CSES serves as a unique monitor of the space weather conditions in the near Earth space.