Comparisons of wind measurements using two different techniques (ground-based radar and satellite) in Brazil during 2006 were made in order to point out the advantages of each instrument for studies in the mesosphere and upper thermosphere. (i) For short-period variations, the measurements of the satellite were more advantageous. (ii) The monthly climatology using the radar was more appropriate. (iii) For long periods (longer than a few months), both instruments responded satisfactorily.

We study how well the F10.7 and F30 solar radio fluxes have represented solar energy input in the thermosphere in the last 60 years. We found that increased saturation of radio fluxes at recent solar minima leads to an overestimation of solar energy, which changes the relation between thermospheric parameters and F10.7, but this is not an issue for F30 because of a relative increase in F30 with respect to F10.7. This explains why F30 has been found to represent solar energy better than F10.7.

The boundary of Earth's magnetic field, the magnetopause, deflects and reacts to the solar wind, the energetic particles emanating from the Sun. We find that certain types of solar wind favour the occurrence of deviations between the magnetopause locations observed by spacecraft and those predicted by models. In addition, the turbulent region in front of the magnetopause, the foreshock, has a large influence on the location of the magnetopause and thus on the accuracy of the model predictions.

We analyzed the average magnetopause position influenced by solar winds and interplanetary magnetic field (IMF) using data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS), Radiation Belt Storm Probes (RBSP), and Magnetospheric Multiscale (MMS) mission from 2016–2020. Minimal movement occurred during substorm phases. The magnetopause moved to its closest inward position during the growth phase and relaxed from peak to recovery as in Shue's model.

The coming seven-spacecraft Plasma Observatory and nine-spacecraft HelioSwarm will achieve seven–nine-point magnetic measurements. In this study, a new algorithm is generated to calculate linear and quadratic magnetic gradients from such magnetic measurements so as to obtain the complete geometry of the magnetic structures observed. The tests verify the feasibility of the method. The algorithm can thus be applied to the analysis of magnetic field data from the Plasma Observatory and HelioSwarm.

The EISCAT_3D radar is a new ionospheric radar under construction in the Fennoscandia region. The radar will make measurements of plasma characteristics at altitudes above approximately 60 km. The capability of the system to make these measurements at spatial scales of less than 100 m using multiple digitised signals from each of the radar antenna panels is highlighted. There are many ionospheric small-scale processes that will be further resolved using the techniques discussed here.

This study explores how solar sunspot number (Sn) compares with other solar indicators like solar radio fluxes in predicting changes in Earth's ionosphere, particularly its critical frequency, over more than 60 years. The work finds that Sn, despite recent fluctuations in other proxies, remains the most stable predictor across all time periods. When adjusting for potential data saturation, Sn outperforms other proxies, providing a more accurate forecast of long-term ionospheric trends.

This study analyzes changes in the ionospheric response to solar flux over five complete solar cycles (1957 to 2023). We use Juliusruh hourly data of the peak electron density of the F2 layer, NmF2, and three solar extreme ultraviolet (EUV) radiation proxies. The response is better represented by a cubic regression, and F30 shows the highest correlation for describing NmF2 dependence over time. These results reveal a decrease in NmF2 influenced by the intensity of the solar activity index.