Forecasting the thermosphere (atmosphere's uppermost layer from 90 to 800 km altitude) is crucial to space mission design, spacecraft operations and space surveillance. Thermosphere is controlled by the Sun, through the highly variable solar EUV radiation and the solar wind. We show how two solar indices, Mg II and Ap, may be used in forecasting thermospheric density at 260 km, a very low altitude where the GOCE satellite has operated from 2009 to 2013, during the full rise of Solar Cycle XXIV.

This paper presents a comprehensive analysis of the solar event occurred on August 25, 2018. This kind of comprehensive analysis plays a key role to better understand the complexity of the processes occurring in the Sun-Earth system that determines the geoeffectiveness of solar activity manifestations. The analysis presented her shows for the first time a direct link among the solar perturbation characteristics, the magnetosphere-ionosphere system response, and the Space Weather effects.

To get the global distribution of the stratification phenomenon, the in situ plasma density measurements, obtained by the Swarm satellites orbiting at different altitudes above F2 peak, are used to study this phenomenon. The continuous morphology of this phenomenon and its features along latitudinal direction are obtained. And a new discovery from the in situ measurements is the stratification on southern mid-latitudes.

Solar storms are natural phenomena that affect technologies in which our societies are highly dependent. The understanding of solar storms and the capability to anticipate their effects on our technologies is of main interest to shield our societies. In this work we present a semi-empirical approach to increase our understanding of solar storms when they hit our planet. We also preset a possible pathway to forecast the transits of solar storms by our planet's orbit.

Pulsating auroras have recently begun to be reconsidered in the context of the conditions and mechanisms driving them. This research connects one type of pulsating aurora to specific plasma waves and uses in situ plasma observations to infer the source region of this aurora. Shortcomings of the available methods of associating in situ observations with specific auroral features are outlined and a key issue is identified which challenges our understanding of pulsating aurora formation.

This study developed a model of Total Electron Content (TEC) over the African region. The TEC data were derived fro radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Geomagnetically quiet time data during the years 2008–2011, and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were used to fit the data for the model.

High-energy electrons in the Earth's magnetosphere can produce operational anomalies in spacecrafts. We investigate the regular variations in these electrons as well as in Pc5 low frequency waves that are capable to generate the electrons. We find that both variables present similar periods in every solar cycle phase. We focus the analysis in the Semiannual Variation of these parameters. The shape of the observational semiannual curves correlate very well with the profiles of the main theories.

Ionospheric irregularities are a common phenomenon in the low latitude ionosphere. In this paper, we compared simultaneous observations of plasma plumes by the JULIA radar, ionogram spread F generated from ionosonde observations installed at the JRO, irregularities observed in situ by Swarm to determine whether Swarm in situ observations can be used as indicators of the presence of plasma plumes and spread F on the ground.

We present a study of ultra-low-frequency waves in the ionosphere and on the ground (geomagnetic pulsations). They can influence particle flux in the magnetosphere, which modify the ionosphere. However, there is no simple dependence between geomagnetic and ionospheric pulsations. We study not only selected pulsations with very high amplitudes but also usual pulsations and try to answer the question, which pulsations' parameters are favorable for modulation of the ionosphere.

Coronal mass ejection sheaths and ejecta are key drivers of significant space weather storms and they cause dramatic changes in radiation belt electron fluxes. Differences in precipitation of high-energy electrons from the belts to the upper atmosphere is thus expected. We investigate here differences in sheath and ejecta induced precipitation using the Finnish riometer chain.

In this work, the correlation between ROTI and S4 is investigated based on a derived mathematical model under the assumption of single screening model for trans-ionospheric signal propagation. The correlation between ROTI and S4 is strongly affected by the variability of the effective velocity, and the correlation coefficient is degraded when the variability increases.The scintillation index S4 depends on the ionospheric irregularities, the effective velocity and the radio propagation path.

Solar atmospheric tides are natural oscillations of 24, 12, 8... hours that contribute to the circulation of the atmosphere from low to high altitudes. Sun heats the atmosphere periodically because, mainly, water vapor and ozone absorb solar radiation between ground and 50 km height during the day. Tides propagate upward and they can be observed in, e.g., wind field. This work presents diurnal tides observed by meteor radar which measure wind between 80 and 100 km height.

Powerful radio waves transmitted into the ionosphere give the strongest turbulence effects in geomagnetic zenith, antiparallel to the magnetic field in the northern hemisphere. Our results obtained with the EISCAT (European Incoherent SCATter association) Heating facility in Norway and the EISCAT UHF incoherent scatter radar together with modeling suggest that the pump wave propagates in the L mode, rather than in the O mode that is usually assumed to be involved in such experiments.