The atmospheric impacts of energetic particle precipitation (EPP) can be useful in understanding the uncertainties of measuring the precipitation. Hence information on how strong of an EPP flux has observable atmospheric impacts is needed. In this study we find such threshold flux values using odd hydrogen concentrations from both satellite observations and model simulations. We consider effects of solar proton events and radiation belt electron precipitation in the middle atmosphere.

We investigate local acceleration dynamics of electrons with a new numerical simulation method, which is an extension of a world-leading kinetic plasma simulation. We describe how large supercomputer simulations can be used to initialize the electron simulations, and show numerical stability for the electron method. We briefly show that features of our simulated electrons match observations from Earth's magnetic tail region.

Long and short period oscillations in the lunar semidiurnal tidal amplitudes in the ionosphere derived from the total electron content were investigated over Brazil from 2011 to 2014. The results showed  annual, semiannual and intra-seasonal as the dominant components. Additionally, The most pronounced short period oscillation was the 7–11 days which presented characteristics compatible with the quasi 10 days planetary wave, suggesting a possible coupling process from the lower atmosphere.

We investigate the dynamics of helium in the foreshock, a part of near-Earth space found upstream of the Earth's bow shock. We show how the second-most common ion in interplanetary space reacts strongly to plasma waves found in the foreshock. Spacecraft observations and supercomputer simulations together give us new understanding of the foreshock edge and how to interpret future observations.

Travelling ionospheric disturbances behave like waves in the ionosphere, the ionised upper part of the atmosphere. In this study, we use an ionospheric tomography technique to map the electron content as affected by the passage of a large scale travelling ionospheric disturbance launched during the largest geomagnetic storm observed by modern instruments. This is the first such imaging using this software and to the authors' knowledge the first study of this travelling ionospheric disturbance.

We present a study of ultra-low-frequency waves in the ionosphere and on the ground. These waves are very slow (their periods are about several minutes). They are registered on the ground as geomagnetic pulsations. No simple dependence exists between geomagnetic and ionospheric pulsations. Here 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.

Plasma waves are ubiquitous in the Earth's magnetosphere. They are responsible for many energetic processes happening in Earth's atmosphere, such as auroras. In order to understand these processes, thorough investigations of these waves are needed. We use a state-of-the-art numerical model to do so. Here we investigate the impact of different spatial resolutions in the model on these waves in order to improve in the future the model without wasting computational resources.

This paper discusses the charge generation for impacts of nano- to micro-scale dust on metal surfaces at speeds below a few km/s. By introducing a model of capacitive coupling between the dust and the impact surface, we find that at such low speeds, the charge can be dominated by contact charging as opposed to plasma generation.

Dust grains exist throughout our solar system. This dust is subject to destruction processes like sublimation and sputtering. Sputtering is the erosion of dust through the impact solar wind and can be very effective near the Sun. We performed calculations to find out how import the sputtering process is compared to the sublimation of dust. Recently started spacecraft will probe the proximity of the Sun and measure the dust population. Our work will help to understand these measurements.

Rapid variations of the magnetic field measured on the ground can be used to estimate space weather risks to power grids, but forecasting the variations remains a challenge. We show that part of this problem stems from the fact that in addition to electric currents in space, the magnetic field variations are strongly affected by underground electric currents. We suggest that separating the measured field into its space and underground parts could improve our understanding of space weather.

This paper studies magnetic field fluctuations in three turbulent sheath regions ahead of interplanetary coronal mass ejections (ICMEs) in the near-Earth solar wind. Our results show that fluctuation properties vary significantly in different parts of the sheath and when compared to solar wind ahead. Turbulence in sheaths resemble that of the slow solar wind than and in terrestrial magnetosheath, e.g., regarding compressibility, intermittency and they often lack Kolmogorov's spectral indices.

This study compares trapped outer radiation belt electron fluxes to high-latitude precipitating electron fluxes during two interplanetary coronal mass ejections (ICMEs). These ICME had opposite magnetic cloud rotation. The electron response had multiple similarities and differences between the two events, indicating that different acceleration mechanisms acted in the two ICMEs. Van Allen probe data were used for trapped electron flux measurements, and POES was used for precipitating flux data.

We have applied three different methods to examine the observability, both tracking and discovery, of near-Earth objects (NEOs) by the EISCAT 3D radar system currently under construction. There are to to our knowledge no previous studies done on the expected discovery-rates of NEOs using radar systems. We show that it is feasible to regularly track NEOs and minimoons. We also show it is possible to discover new NEOs and minimoons with EISCAT 3D, something never before done with radar systems.