The standard linear fluid theory of Farley and Buneman predicts that kinetic physics are required to avoid the artificial growth of smaller structures. We explore the possibility of simulating the Farley–Buneman instability using, for the first time, a fully fluid five-moment model. This is the first time a fully fluid model has been used to simulate the Farley–Buneman instability. The results obtained with both models are qualitatively consistent with the ones from kinetic simulations.

The solar cycle affects the H₂O concentration in the upper mesosphere mainly in two ways: directly through photolysis and, at the time and place of NLC formation, indirectly through temperature changes. The H₂O–Lyman-α response is modified by NLC formation, resulting in a positive response at the ice formation region (due to the temperature change effect on the ice formation rate) and a negative response at the sublimation zone (due to the photolysis effect).

Earth’s space environment is populated with charged particles. The energetic ones are trapped around Earth in radiation belts. Orbiting spacecraft that cross their region can accumulate charges on their internal surfaces, leading to hazardous electrostatic discharges. This paper showcases the SafeSpace safety prototype, which aims to warn satellite operators of probable incoming hazardous events by simulating the dynamics of the electron radiation belts from their origin at the Sun.

In this work, we analyzed and compared measurements of electron fluxes in the radiation belts from two instruments with different orbits. In the outer belt, where the altitude difference is the largest between the two instruments, we find that the observations are in good agreement, except during geomagnetic storms, during which fluxes at low altitudes are much lower than at high altitudes. In general, both at low and high altitudes, the correlation between the instruments was found to be good.

The solar wind is in a plasma state and can exhibit a range of phenomena like waves and instabilities. One observed phenomenon in the solar wind is magnetic holes (MHs). They are localized depressions in the magnetic field. We studied the motion of MHs using the multispacecraft ESA Cluster mission. We derived their velocities in the solar wind frame and found that both linear and rotational MHs are convected with the solar wind.

The relation between electron, ion and neutral temperatures in the lower thermosphere–ionosphere (LTI) is key to understanding the energy balance and transfer between species. However, their simultaneous measurement is rare in the LTI. Based on data from the AE-C, AE-D, AE-E and DE-2 satellites of the 1970s and 1980s, a large number of events where neutrals are hotter than ions are identified and statistically analyzed. Potential mechanisms that could trigger these events are proposed.

We dealt with the most intense magnetic storm of the 20th century, which took place on 13–15 May 1921. It was also observed at Stará Ďala (present-day Hurbanovo). However, the record was not complete. We estimated the missing sensitivity scale values and presented the resulting digitized Stará Ďala’s data for 13–15 May 1921. The data were compared with the records from other observatories. The analysis suggests that the auroral oval got close to Stará Ďala in the morning hours on 15 May 1921.

Transverse electric fields transmitted from the magnetosphere and those generated by the neutral winds yield a local breakdown of the charge neutrality at the boundaries between the thermosphere and mesosphere. The breakdown may create parallel electric fields in the thermosphere to produce spiral auroras and outflows. This explanation supposes an auroral generator located not in a distant space, but rather in our much nearer upper atmosphere.

We improve a method for modeling the interaction between solar wind and Mars that uses a hybrid model to fit the observed bow shock location to determine a corresponding exobase ion upflux. We applied the method to one Mars Atmosphere and Volatile Evolution orbit to study the effects on ion escape estimates of heavy-ion composition in the ionosphere, alpha particles in the solar wind, solar-wind velocity aberration, and electron temperature. We also studied the morphology of the escaping ions.

Freshly created ions in solar wind start gyrating around the interplanetary magnetic field. When they cross the bow shock, they get an extra kick, and this increases the plasma pressure against the magnetic pressure. This leads to the creation of so-called mirror modes, regions where the magnetic field decreases in strength and the plasma density increases. These structures help in exploring how energy is transferred from the ions to the magnetic field and where around Venus this is happening.

Gravity waves (GWs) are waves in Earth's atmosphere and can be observed as cloud ripples. Under certain conditions, these waves can propagate up into the ionosphere. Here, they can cause ripples in the ionosphere plasma, observable as oscillations of the plasma density. Therefore, GWs contribute to the ionospheric variability, making them relevant for space weather prediction. Additionally, the behavior of these waves allows us to draw conclusions about the atmosphere at these altitudes.

We derive the wave–particle interaction time (IT) equation considering the effects of special relativity theory for whistler-mode chorus waves and relativistic electrons in Earth's radiation belt. Results show that IT has a non-linear dependence on the wave group velocity, electrons' energy, and initial pitch angle. Our results show that the interaction time is generally longer when applying the complete relativistic approach compared to a non-relativistic calculation.

The upper detection limit in reciprocal space, the spatial Nyquist limit, is derived for arbitrary spatial dimensions for the wave telescope analysis technique. This is important as future space plasma missions will incorporate larger numbers of spacecraft (>4). Our findings are a key element in planning the spatial distribution of future multi-point spacecraft missions. The wave telescope is a multi-dimensional power spectrum estimator; hence, this can be applied to other fields of research.

We used the spherical harmonic function (SHF) and the local spherical symmetry (LSS) assumption methods to calculate the hourly and daily LEO satellite GPS differential code bias (DCB). The SHF method is more stable and precise than the LSS assumption. The daily DCB estimation is more accurate and stable than the hourly DCB due to more observation data. Hourly DCBs have large changes in one day, mainly be attributed to random errors because these error time series have a normal distribution.

At times when auroras erupt on the sky, the magnetic field surrounding the Earth undergoes rapid changes. On the ground, these changes can induce harmful electric currents in technological conductor networks, such as powerlines. We have used magnetic field observations from northern Europe during 28 such events and found consistent behavior that can help to understand, and thus predict, the processes that drive auroras and geomagnetically induced currents.

We use computed tomography to reconstruct the three-dimensional distributions of the Hall and Pedersen conductivities of pulsating auroras, a key research target for understanding the magnetosphere–ionosphere coupling process. It is suggested that the high-energy electron precipitation associated with pulsating auroras may have a greater impact on the closure of field-aligned currents in the ionosphere than has been previously reported.

Substorms are a phenomenon in the magnetosphere–ionosphere system, which are characterised by brightening of an auroral arc and enhancement of electric currents in the polar ionosphere. Since substorms are difficult to predict, this study treats a substorm occurrence as a stochastic phenomenon and represents the substorm occurrence rate with a machine learning model. We then analyse the response of substorm activity to solar wind conditions by feeding synthetic solar wind data into the model.

According to plasma drift theory, charged particles will drift when they are subjected to external forces, thus generating a drift current. In this paper, we establish the drift current and magnetic perturbation model in the ionosphere. Based on the HAARP ionospheric background, we analyze the properties of drift current and magnetic perturbation. This work provides guidance for a better understanding of ionospheric current distributions and magnetic perturbations.

Magnetosheath jets are structures of enhanced plasma density and/or velocity in a region of near-Earth space known as the magnetosheath. When they propagate towards the Earth, these jets can disturb the Earth's magnetic field and cause hazards for satellites. In this study, we use a simulation called Vlasiator to model near-Earth space and investigate jets using case studies and statistical analysis. We find that jets that propagate towards the Earth are different from jets that do not.

The plasma environment of comet 67P provides a unique laboratory to study plasma phenomena in the solar system. Previous studies have reported the existence of mirror modes at 67P but no further systematic investigation has so far been done. This study aims to learn more about these waves. We investigate the magnetic field measured by Rosetta and find 565 mirror mode signatures. The detected mirror modes are likely generated upstream of the observation and have been modified by the plasma.

Powerful radio waves transmitted into the ionosphere from the ground were used to study electron energization in the pumped ionospheric plasma turbulence, by detecting optical emissions from atomic oxygen. Our results obtained with the EISCAT (European Incoherent Scatter Scientific Association) facilities in northern Norway and optical detection with the ALIS (Auroral Large Imaging System) in northern Sweden suggest that long-wavelength upper hybrid waves are important in accelerating electrons.