Interplanetary dust also includes very small (nanometer-sized) particles. The dynamics of nanodust is determined by electromagnetic forces, which accelerate the dust to velocities on the order of 500 km s⁻¹ or, in the vicinity of the Sun, trap them in bound orbits. We investigate the behavior of nanodust during a coronal mass ejection. We find a new population of extremely fast (1000 km s⁻¹) nanodust. We also study the effect of the ion drag force.

From computer simulations we study how free electrons behave in a region where opposite magnetic fields interact. The particles get disturbed and change their velocity and energy, similar to what happens in the tail of the magnetic field on the nightside of the Earth or during magnetic outburst events on the Sun. We provide a catalog of those particle velocities that are specific to their location within the magnetic field. Scientists may use the data for comparison with satellite observations.

Large-scale undulations of the diffuse aurora boundary, auroral omega bands, have been studied based on 438 omega-like structures identified over Fennoscandian Lapland from 1996 to 2007. The omegas mainly occurred in the post-magnetic midnight sector, in the region between oppositely directed ionospheric field-aligned currents, and during substorm recovery phases. The omega bands were observed during substorms, which were more intense than the average substorm in the same region.

For regional studies and practical use regional-scale models of the geomagnetic field are necessary. The Bulgarian Geomagnetic Reference Field (BulGRF) for 2015.0 epoch and prediction up to 2020.0 is produced and presented in this paper. It uses data from Panagyurishte (PAG) observatory and the Bulgarian secular network. As a result, our model gives a set of six coefficients which allow the users to obtain the main field values using only the geographic coordinates and a simple calculator.

We examine the wave activity that can possibly develop in the foot of quasi-perpendicular plasma shock, as it arises from the relative drifts of three particle populations across the background magnetic field: ions incoming toward the shock, ions reflected from the shock, and electrons. The goal is to consider the role of different wave propagation angles with respect to the magnetic field. Three types of instabilities are identified which could play a role in shock dissipation.

Ionospheric disturbances observed in Antarctica during a moderately strong geomagnetic storm caused by the impact of a coronal mass ejection from the Sun are presented here. The ionosphere behavior was analyzed using GNSS and ionosonde observations at middle and high latitudes. The results showed that the impact promptly affected the ionosphere from the Equator to the high latitudes, resulting in strong irregularities, particularly at middle and high latitudes, which can affect GPS users.

In this study, we statistically analyzed severe magnetic fluctuations in the nightside near-Earth plasma sheet. For the first time, we showed the occurrence rates of these fluctuations. The superposed epoch analysis also indicated that the flow speed increases before the severe magnetic fluctuations. We also discussed how both the inside-out and outside-in substorm models can be used to explain these observed results.

Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. A plasma line gives an accurate measure of the electron density and can be used to estimate electron temperature. The occurrence of plasma line enhancements in the EISCAT Svalbard Radar data was investigated. During summer daytime hours the plasma line is detectable in up to 90 % of the data. In winter time the occurrence is a few percent.

Information on the mesospheric OH layer height is crucial for identifying sources of its variability and causes of discrepancies in measurements and models. Using space-based data, we inferred an empirical function for predicting the altitude of the layer at midlatitudes from ground-based measurements of OH intensity and temperature. By applying it to data at the Sierra Nevada Observatory, we found significant short-term variability in the layer altitude, mainly due to wave variability.

In this work the response of the Brazilian equatorial ionosphere is studied during three HILDCAA events that occurred in the year of 2006 using the digisonde data. Geomagnetic indices and interplanetary parameters were used to calculate a cross-correlation coefficient between the E_y and the hmF2. The results showed that the pumping action of particle precipitation into the auroral zone has moderately modified the equatorial hmF2, being more sensitive during PRE time.