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 latitude region from 10° N to 30° N. Theoretical analysis indicates that these currents are originated from the fluctuation of magnetic field lines during strong geomagnetic storms.

During the night, in the F-region, equatorial ionospheric irregularities manifest as plasma depletions observed by satellites and may cause radio signals to fluctuate. We checked the distribution traits of ionospheric F-region irregularities in the low latitudes using 16 Hz electron density observations made by the faceplate on board Swarm satellites. Using the high-resolution faceplate data, we were able to identify ionospheric irregularities of scales of only a few hundreds of meters.

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 being as the first-order fluctuation). We refer to the simultaneous decay as multi-channel couplings following the notion in the scattering theory. Our goal is to study the hypothesis of the multi-channel coupling by running a three-dimensional hybrid plasma simulation.

We report long-term observations of atmospheric parameters in the mesosphere and lower thermosphere made over the last two 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. While climatologies show a similar pattern, does seasonal tendencies differ strongly regarding location and altitude.

In this work we present an analysis of the dynamics of suprathermal ions of different masses (H⁺, He⁺, O⁺) during prolonged dipolarizations in the near-Earth magnetotail according to Cluster/RAPID observations in 2001–2005. All dipolarizations from our data base were associated with fast flow braking and consisted of multiple dipolarization fronts (DFs). We found statistically that fluxes of suprathermal ions started to increase ~ 1 min before the dipolarization onset and continued.

We analyzed the forcing mechanisms of the 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 and also the background circulation in the thermosphere.

The Brazilian Space Weather Study and Monitoring Program (Embrace) has been developing different indexes that describe the ionospheric effects for the Brazilian sector. Therefore, 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 8 years of in order to construct a standardized scale. The results of this new index allow us evaluating the impacts of ionospheric phenomena in the Space Weather environment.

The composition of the upper atmosphere has been difficult to measure with localised observations relying on spacecraft or sub-orbital rockets or measurements of airglow from ground-based observatories. The height profile of ionisation within the neutral upper atmosphere is influenced by the composition of the neutral gas. We present a method for determining the neutral upper atmosphere composition from measurements of the ionisation profile, and compare these with spacecraft measurements.

The performance of IRI-2016 model in simulating GPS-TEC is assessed based on various statistical tools during two distinct solar activity periods. In particular, the categorical metrics used in the study to assess the the performance of the empirical and climatological IRI-2016 model at the margins of TEC distribution reveal remarkable skill of the model in simulating the observed tails of TEC distribution, which is by far better than accurately simulating the observed climatology as designed.

During the most intense storm of the solar cycle 24, the magnetosphere-ionosphere interaction, which is primarily associated with field-aligned currents (FAC) and particle precipitation, was much stronger than usual. Measurements onboard the polar-orbiting satellite show that the equatorial boundaries of FAC are shifted equatorward as low as 50° MLat. The intensities of FAC increase dramatically the peaks of the storm-time substorm. The extreme instantaneous FACs is up to ~80 μA/m².

The paper focuses on the analyses of the global occurrence of equatorial plasma bubble events using S4 data that was calculated from GPS radio occultation measurements of the FormoSat-3/COSMIC mission. The advantage in using radio occultation data is that, we do not only get information on the occurrence and intensity of the equatorial bubble events but also on its altitude distribution. We analyzed 9 years time series of COSMIC data and could demonstrate a strong dependence on the solar cycle.

We describe a technique used to locate and classify critical points in 2D flow fields at the solar photosphere obtained from the evolution of the line-of-sight magnetic field, in a region close to the magnetic polarity inversion line of a fully emerged active region. We apply this technique to locate a particular kind of critical point is associated to vortex flows, which are considered important since they can twist and interweave the footpoints of flux-tubes and generate magnetic reconnection.

We investigated the statistical relationship between solar activity and occurrence rate of major sudden stratospheric warmings (MSSWs). For this purpose, F10.7 radio flux has been used as a proxy for solar activity. The calculations have been performed based on two datasets of central day (NCEP-NCAR-I and combined ERA) for the period from 1958 to 2013. The analysis revealed a positive correlation between MSSW events and solar activity.

We investigate the ionospheric response to the temporal and spatial dynamics of the solar activity using total electron content (TEC) maps and multiple solar proxies. The maximum correlation at 16–32 days time scale is observed between the He-II, Mg-II, and F30 with respect to global mean TEC, with an effective time delay of about one day. The most suitable proxy to represent the solar activity at the time scales of 16–32 days and 32–64 days is He-II.

The paper presents the variability of thermal tides in the middle atmosphere from temperature observations as well as from horizontal wind data using a new diagnostic approach which takes into account a possible intermittency of tides. The data is analyzed from a local as well as from a global perspective to distinguish between different tidal modes. Surprisingly, there are dominating tidal modes, which are seen in the local data and a phase relation between temperature and winds is evaluated.

When studying the Rayleigh-Taylor instability (RTI) in the ionosphere, I found that the physical description of RTI in ionosphere attribute the growth of RTI to charge accumulation, however, the current continuity equation was used during the calculation of the linear growth rate. Also, the linear growth rate widely used tends to infinity when the collision frequency tends to zero. In this paper, we derived the linear growth rate of RTI and rectified the physical description of the RTI process.

Integrated Water Vapor (IWV) values from ERA-Interim and MERRA-2 were compared to IWV from GNSS at 53 stations of Central and South America during a 7-year period (2007–2013). The comparison takes into account the geopotential height differences and the mean IWV value at each station. The discrepancies between IWV from the models and IWV GNSS raise as the geopotential height difference grows. We proposed a numerical correction that compensates this effect and it was tested with IWV ERA-Interim.

The density distribution of ice particles and electrons near the boundary of PMSE region is studied. The results show that when the radius distribution function of condensation nucleus is Gaussian type, for a certain range of the condensation core radius, sharp peaks with scale of meters appear in the density profiles of ice particles and electrons. These small-scale structures of electron density may be one of the reasons of PMSE phenomenon.

Severe meteorological storm Fabienne passing above Central Europe was observed. Significant variations of atmospheric and ionospheric parameters were detected. Above Europe, stratospheric temperature and wind significantly changed in coincidence with frontal transition. Within ionospheric parameters, we have detected significant wave-like activity shortly after the cold front crossed the observational point. During the storm event, we have observed strong horizontal plasma flow shears.

In this paper, we summarize the anomalous phenomena that have been observed before the super-giant earthquake of magnitude 9.0 that occurred on 11 March 2011 in Japan. These phenomena have been detected by means of ground based measurements and satellite data. We find that all these phenomena are in agreement with a condensed matter physical model that motivated in the 1980s a short-term earthquake prediction method based on the detection of precursory electric signals.

In this paper, for the first time, absolute gravity wave momentum flux (GWMF) on temporal scales from terannual variation up to solar cycle length are investigated. The systematic spectral analysis of SABER absolute GWMF are presented and physically interpreted. The various role of filtering and oblique propagating is discussed which is likely an important factor for MLT dynamics, and hence can be used as a stringent test bed of the reproduction of such features in global models.

The paper describes an approach to model VTEC from NRT GNSS observations only by generating a Multi-Scale-Representation (MSR) based on B-splines. The unknown model parameters are estimated by means of a Kalman-Filter. A number of products have been created which differ both in their spectral and temporal resolution. The validation studies show that the product of highest resolution, based on NRT input data is of higher accuracy than other used within the selected time span of investigation.

Some systems, such as Over the Horizon Radars, use the ionosphere as a reflector for HF radio signals. In this work, HF propagation through the ionosphere is studied for different Earth’s magnetic field configurations during reversals using a numerical ray tracing technique. Our purpose is to highlight possible effects of dipole decrease, which is currently ongoing, on electromagnetic wave propagation through the ionosphere.

The equatorial spread F (ESF) is a nighttime phenomenon which has the potential to have a deleterious effect on the radio communication system. We investigated the parameters influencing the seasonal morphology of the ESF using the ionosonde data taken at different longitudinal sectors. The ESF occurrence features including the onset time and seasonal asymmetry showed distinct patterns across these sectors. The gravity wave was identified as a significant factor to these seasonal distributions.

This paper describes the aerosol measurements setup and results obtained during the BEXUS18 stratospheric balloon within the A5-Unibo (Advanced Atmospheric Aerosol Acquisition and Analysis) experiment performed on October 10th, 2014 in northern Sweden (Kiruna). The experiment and the results here presented broaden the understanding of the processes linking the presence of charges with particles all over the vertical heights from ground to the stratosphere.