This study presents some example events in which sudden changes in the auroral activity at midnight sector seem to have an impact on the intensity of morning-sector magnetic pulsations. Mechanisms which could link these two separate regions are discussed in the paper. Sudden changes in the solar wind properties and fast westward-propagating electrons are suggested to explain the coupling between midnight-sector and morning-sector phenomena.

This study presents an investigation on the occurrence of fast flows in the magnetotail using the complete available data set of the THEMIS spacecraft for the years 2007 to 2015. First, basic statistical findings concerning velocity distributions, occurrence rates, group structures and key features of 16 000 events are presented using Superposed Epoch and Minimum Variance Analysis techniques.

A comparative study of the quasi-16-day wave in the middle from three Brazilian stations, indicates multiple modes of the concerned wave component. The wave amplitude shows maxima in summer and winter. A potential coupling of the concerned wave with other short period planetary waves is found. The dominant wave components vary from the westward to eastward from the tropical to mid-latitude in the stratosphere. The prevailing westerly wind may favor the wave filtering of westward waves.

Electrical resistivity can influence the occurrence of shock waves. We derive analytically necessary conditions for shocks in a nonuniform resistive magnetohydrodynamic plasma. The nonuniform resistivity significantly modifies the characteristic velocity of wave propagation. A sufficient gradient of the resistivity in a diffusion region can satisfy the necessary condition for the occurrence of slow shocks, which is related to Petschek reconnection.

Power transmission lines above the ground, cables and pipelines, and, in general, all man-made long grounded conductors are exposed to the variations of natural electromagnetic field of wide frequency range. This interference often can compromise the systems operations. Paper offers frequency dependent approach in modelling the response of these systems to the geomagnetic variations. The formulas were proposed, analysed, verified and recommended for use in space weather applications.

We investigate the effect of data gaps for various methods of estimating the amplitude spectrum of a time series. We probe the effects of a single data gap of varying size and of numerous small gaps distributed within the time series. We use synthetic data sets and magnetic field measurements from the Venus Express spacecraft. For multiple gaps and turbulent magnetic data, we show that some advanced methods overestimate the high frequencies, while FFT slightly underestimates them.

The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE are investigated. The absolute amplitudes of DE3 at low latitudes as well as DE1, D0 and DW2 at middle latitudes are highly related to the solar activity, while their relative amplitudes show little dependence on the solar activity. A clear modulation by the QBO is found in the relative amplitudes of DE3 at low latitudes.

This work provides an alternative approach to examine one commonly occurring type of electromagnetic waves in Earth's inner magnetosphere. In certain wave modes, the waves propagate along individual field lines of Earth's magnetic field. Governed by the coupled system between the magnetic field and ionized gas of low temperature, the waves show certain characteristics similar to standing waves along an elastic string. We present solutions in agreement with spacecraft observations.

Extreme value analysis has been applied to 1-minute-resolution magnetic fields and computed electric fields over Europe. We find that on average the largest disturbances of the fields are observed close to the auroral oval, as expected. However, the analysis indicates that as we move south from Scandinavia to northern continental Europe the distribution becomes more extreme. This could be due to that strong storms regularly occur at high latitudes, while the extreme storms push the oval south.