Radar observations of the E- and F-region ionosphere from the Arecibo Observatory made during moderately disturbed conditions are presented. Plasma irregularities in both ionospheric regions were observed. We investigate the role of neutral atmospheric dynamics and instabilities in causing the ionospheric disturbances. A number of viable instability mechanisms rooted in neutral dynamics are identified.

We have simulated the interaction of the solar wind – the charged particles and magnetic fields emitted by the Sun into space – with the magnetic field of the Earth. The solar wind flows supersonically and creates a shock when it encounters the obstacle formed by the geomagnetic field. We have identified a new chain of events which causes phenomena in the downstream region to eventually cause perturbations at the shock and even upstream. This is confirmed by ground and satellite observations.

Ion outflow from the ionospheric regions at the highest latitudes is mainly driven by solar illumination. It is an important factor affecting atmospheric escape and space weather. But this region rotates into and out of the sunlight on a daily and seasonal basis. This creates daily and seasonal variations in the outflow, even with both hemispheres combined. The north–south asymmetry in Earth's magnetic field causes extra variations and asymmetries. This was studied with a simple empirical model.

We extend the kriging of the ionospheric electron density with slant total electron content (STEC) measurements based on a spatial covariance to kriging with a spatial–temporal covariance and develop a novel tomography approach by gradient-enhanced kriging assimilating STEC and F2 layer characteristics. The methods are cross-validated with independent measurements and point out the potential compensation for the often observed bias in the estimation of the F2 layer peak height.

Dayglow emission variability is expected to show a symmetric solar zenith-angle-dependent diurnal pattern as the production mechanisms are dominated by solar flux; however, this is not always the case. Our investigation reveals an imprint of equatorial electrodynamics on the neutral dayglow emission variability, as opposed to that of the solar zenith angle. This has implications in gaining a comprehensive understanding of the coupled nature of the ion-neutral behaviour in the upper atmosphere.

The Middle East capitals are subjected to numerous dust storms along with local emissions and/or those transported from biomass burning or industrial activities. A combination of these aerosols results in poor air quality and poses significant health hazards. We investigated the transport of aerosols and their impact on the air quality using different parameters derived from the AERONET ground observations.

Two traveling ionospheric disturbances (TIDs) were observed by the GPS network in Asia following the large meteorite blast over Chelyabinsk, Russia. No TIDs propagating in a global range were found. Features of TIDs were compared with those excited by early nuclear explosion tests. It is inferred from our analysis that the energy release of the Chelyabinsk meteorite blast may not be large enough to excite such ionospheric disturbances in a global range as some nuclear explosions have done.

We investigate the time variation of the magnetospheric and Earth's magnetic field during both quiet and disturbed periods. We identify the timescale variations associated with different magnetospheric current systems, solar-wind–magnetosphere high-frequency interactions, ionospheric processes, and internal dynamics of the magnetosphere. In addition, we propose a new local index for the identification of the intensity of a geomagnetic storm on the ground.

From the data on the protons of the Earth’s radiation belts, the rate of radial diffusion of these particles is directly calculated. This is done by solving the systems of equations which describe the balance of radial transport/acceleration and ionization losses of protons. These results are very consistent with the radial diffusion of particles under the influence of the electric field pulsations in the range of the drift frequencies of the protons around Earth.

The behaviour of mirror mode waves in Venus's magnetosheath is investigated for solar minimum and maximum conditions. It is shown that the total observational rate of these waves does not change much; however, the distribution over the magnetosheath is significantly different, as well as the growth and decay of the waves during these different solar activity conditions.