Higher total electron content (TEC) day-to-day variations during the daytime than at night were observed for all years. The diurnal variation shows observed TEC (OBS-TEC) rising rapidly from a minimum just before sunrise at 03:00–05:00 LT (∼2 TECU) in 2011, 04:00–05:00 LT (∼3 TECU) in 2012, 03:00–05:00 LT in 2013 (∼3 TECU) and 03:00–05:00 LT in 2014 (∼3 TECU). OBS-TEC is found to increase to a broad daytime maximum at 00:12–00:16 LT for all years before falling to a minimum after sunset.

When the terrestrial magnetic field is disturbed, particles from the near-Earth space can precipitate into the upper atmosphere. This work presents, for the first time, numerical simulations of proton precipitation in the energy range associated with the production of aurora (∼1–30 keV) using a global kinetic model of the near-Earth space: Vlasiator. We find that nightside proton precipitation can be regulated by the transition region between stretched and dipolar geomagnetic field lines.

The Brazilian Space Weather Study and Monitoring Program (Embrace) has been developing different indexes that describe ionospheric effects in the Brazilian sector. The main purpose of this work was to produce a new ionospheric scale based on the analysis of the ionospheric plasma drift velocity. We analyzed 7 years of data in order to construct a standardized scale. The results of this new index allow us to evaluate the impacts of ionospheric phenomena in the space weather environment.

The paper discusses a problem concerned with the excitation of chorus with small wave normal angles along the external magnetic field in the magnetosphere. We examine the realisation of the beam pulse amplifier mechanism of chorus excitation without strong anisotropy of the plasma particle distribution function in the density ducts with refractive reflection. It is shown that in the ducts, discrete spectral elements of chorus can be excited at close to half of the electron cyclotron frequency.

Scaling laws and energy spectra for the electric field, magnetic field, flow velocity, and density are theoretically derived for small-scale turbulence in space plasma on which the electrons behave as a fluid but the ions more as individual particles due to the difference in the mass (the Hall effect). Our theoretical model offers an explanation for the small-scale turbulence spectra measured in near-Earth space.

Here we present a scenario that the decay of a field-aligned Alfvén wave can occur simultaneously at various angles to the mean magnetic field, generating a number of second-order fluctuations or waves (after the pump wave as the first-order fluctuation). We refer to the simultaneous decay as multi-channel couplings following the notion in scattering theory. Our goal is to study the hypothesis of the multi-channel coupling by running a three-dimensional hybrid plasma simulation.

We report on long-term observations of atmospheric parameters in the mesosphere and lower thermosphere made over the last 2 decades for the northern-latitude locations of Andenes, Juliusruh, and Tavistock. The observations are based on meteor wind measurements and further include the long-term variability of winds, tides, and the kinetic energy of gravity waves and planetary waves. Furthermore, the influence on an 11-year oscillation on the winds and tides is presented.

Earth's bow shock in solar wind with high thermal and low magnetic pressure is a rare phenomenon. However, such an object is ubiquitous in astrophysical plasmas. We surveyed statistics of such shock observations since 1995. About 100 crossings were initially identified. In this report 22 crossings from the Cluster project were studied using multipoint analysis, which allowed for the determination of the spatial scales of the shock transition and of the dominant magnetic variations

Solar jets driven by heat or pressure pulses at their footpoints in the photosphere transfer energy and mass in to the corona. These jets energize the coronal part of the atmosphere with collimated plasma, similar to the fluid filled in a pipe. Understanding the physical drivers of such jets is of great significance to study the plasma in confined magnetic fields. The modelled jets in our paper allow for the study of the evolution of chromospheric plasma and support many existing observations.

We analysed data from radiation monitors aboard different spacecraft such as Rosetta and Integral. From the data, we extracted the evolution of galactic cosmic rays as a function of time (over a full solar cycle) and position (from 1 to 4.5 AU). In the main results, we confirm the overall evolution (anti-correlation) of the fluxes with respect to the solar activity. We found a surprising result, which is a decrease in the flux of galactic cosmic rays around comet 67P.

The wavelet transform was employed in nine HILDCAA events for intervals in which the Cluster crossed the magnetotail in order to identify the most energetic periods of these events in the magnetotail. It was seen that 76 % of the periods identified are ≤4 h. Using the cross wavelet analysis technique between B_z–IMF components and the B_x geomagnetic components, it was identified that the coupling of energy is stronger in periods between 2 and 4 h, which are typical substorm periods.

Previous studies show that the ring current (RC) and field-aligned currents (FACs) are the dominant currents in the inner magnetosphere. However, through two large storm events observed by Cluster, we find new strong southward and northward currents in the latitudinal region from 10° N to 30° N. Theoretical analysis indicates that these currents originated from the fluctuation of magnetic field lines during strong geomagnetic storms.

We analyzed the forcing mechanisms of the migrating terdiurnal solar tide in the middle atmosphere, focusing the impact on the zonal mean circulation. We show that the primary solar forcing is the most dominant one but secondary wave–wave interactions also contribute in the lower thermosphere region. We further demonstrate that small-scale gravity waves can strongly and irregularly influence the amplitude of the terdiurnal tide as well as the background circulation in the thermosphere.

Our numerical simulation shows that the drag due to the dissipation and/or breaking of the gravity wave plays an important role in the general circulation in the thermosphere. This means that the parameterization for the gravity wave drag is necessary for numerical simulation in the thermosphere.

The mirror mode starts as a zero-frequency ion fluid instability and saturates quasi-linearly at very low magnetic level, while forming extended magnetic bubbles. These trap the adiabatically bouncing electron component which forms pairs near the mirror points. The large pair anisotropy causes further growth beyond quasilinear level. Including pressure equilibrium gives and estimate of the required pair density.

Atmospheric drag due to mass density distribution, particularly during storm-time, is of great importance for low Earth orbit precise orbit determination, and for the understanding of magnetosphere–ionosphere–thermosphere phenomena. In this paper, we investigate solar cycle, seasonal, and hemispheric asymmetry dependencies of thermospheric mass density disturbances due to magnetospheric forcing, from 10-year (2003–2013) continuous time series of GRACE estimates.