Observations of flapping current sheet in the magnetotail are presented to reveal their intrinsic excitation mechanism induced by alternating north-south asymmetric ion populations in the sheet center. The results suggest that nonadiabatic ions play a substantial role to determine current sheet dynamics, both its bulk mechanical instability and current profiles.

The interplanetary magnetic field is a consequence of the solar magnetic field and the solar wind. Different magnetic field models exist in literature that allow to better understand how the solar field extends throughout the solar system. We highlight different aspects of these different interplanetary magnetic field models and discuss possible applications. Verification of these models will become possible using data from the Parker Solar Probe and Bepi-Colombo space mission.

We observe the planetary and gravity wave activity in the vertical profile of ozone at the mid- European ozonosonde stations The performance of the used detection method is satisfactory. There are differences in the following characteristics of the structure caused by the planetary and gravity wave: the annual variation, the size, the vertical distribution and trend. The results are influenced by the ozonosonde vertical resolution only for small and medium structures.

Occasional deviations in density and magnetic power spectral densities in an intermediate frequency range are interpreted as ion response to the Kolmogorov turbulent velocity spectrum.

Receivers and Satellites Differential Code Biases (DCBs) are one of the main error sources in estimating precise Global Ionosphere Maps (GIMs) from Global Positioning Systems (GPS) data. This paper introduces a mathematical model for estimating satellites & receivers DCBs from A GPS network written under MATLAB environment. Our code was tested and compared with Ionosphere Associated Analysis Centers (IAAC) and other researchers' codes results. The results shows an improvement for estimated DCBs.

This study is concerning of the postmidnight ionospheric irregularities observed during low solar activity conditions. We analyze data from digisondes and optical imaging systems located at equatorial region over Brazil. The results show that they occur under unfavorable and unexpected conditions. This work can be useful for Space Weather forecasting during low solar activity.

Sporadic E (E_S) layers in the Earth’s lower ionosphere are produced by ion convergence due to vertical wind shear in the presence of a horizontal component of the Earth magnetic field. The wind shear is provided mainly by solar tides. We present analyses of the 6-hr tidal signatures in E_S occurrence rates derived from GPS radio observations. Times of maxima in E_S agree well with those of negative wind shear obtained from radar observations and modelling.

The Earth’s radiation belt (ERB) is formed by energetic particles caught in the geomagnetic trap. Within the last two solar cycles (from 2001 to 2018), observation of the ERB by a fleet of low-altitude POES satellites allowed to find an abnormal equatorward displacement of the outer part of ERB in the Siberian sector. The displacement can partially explain an increase in the occurrence rate of mid-latitude aurora borealis observed in the Eastern Hemisphere.

During observations of the electromagnetic waves onboard Vernov satellite in 2014 some interesting phenomena were discovered. They are connected to non-linear effects in wave activity of the type of two or three wave decays as well as splitting into two wave structures. Whistlers with specific unusual temporal structure of swallowtail type were observed. It was shown that such signals can be caused by seismic activity.

Turbulence dissipation rate has inter-annual variations and follows a lognormal distribution. The magnitudes of turbulence detected by radiosonde and radar are roughly comparable. Turbulence cannot predicted by instabilities well but trends to be vigorous under the instability condition. The propagating gravity waves in the lower atmosphere can enhance atmospheric instabilities, and the temporal variations of waves can roughly estimate the turbulence dissipation rate at different height.

Ionospheric disturbances can be generated by human activities such as underground Nuclear Explosion (UNE) through LAIC mechanism. By using the GNSS and SWARM observations, we have investigated the geomagnetic conjugate ionospheric disturbance. We proposed that electric field generated by UNE can be an important mechanism for ionospheric disturbance. This electric field can map to the conjugate hemisphere along the magnetic field line and cause ionospheric disturbances in conjugate regions.

The GPS radio occultation data of the COSMIC-FORMOSAT-3 mission are used to visualize the global distribution of ionospheric irregularities in the F2 region during a geomagnetic storm, at solar minimum, and at solar maximum.

Decidated to the combined analysis of space weather data (geomagnetic activity, cosmic ray secondaries and ionospheric data) obtained during the September 2017 solar flares and geomagnetic storms, this study is an attempt to construct a technique for circumterrestrial physical data analysis in order to analyze various space weather effects and obtain new mutually supportive information during major space weather events on different phases of geomagnetic storm evolution.

We have over viewed an algorithm which can be used to estimate ionospheric delays of GPS observations using single GPS receiver using a spherical ionospheric shell model. This Algorithm depends on the geometry-free carrier-phase observations after detecting cycle slip. The ionospheric estimation in this algorithm is performed by means of Sequential least-squares adjustment. This study is performed on ten IGS stations, and results of the ionosphere delay was compared with GAPS software results.

We propose that the temperature of the Na exosphere of Mercury near the sub-solar point is not at high as proposed in previous works. Using a numerical model and the appropriate energy distributions for each release mechanism we can explain observations made by MESSENGER in April 2012. Our results show that close to the surface the dominant release mechanism for Na is evaporation due to the solar irradiation, and at high altitudes the best candidate is the release by micro-meteoroid impacts.

We use data from two NASA satellites and a general circulation model of the upper atmosphere to elucidate the key factors governing the abundance and diurnal variation of nitric oxide (NO) at near solar minimum conditions and low latitudes. This has been difficult to do previously because NO data are typically taken from satellites in sun-synchronous orbits, which means they only acquire data in fixed local times. We overcome this limitation through model simulations of the NO diurnal cycle.

The comparison of geomagnetic active and quite events of double substorm onsets responsive to IMF variations shows that the occurrence sequence of all required substorm signatures looks the same and not different for small and large Kp. Double substorm onsets responsive to IMF variations can be characterized with two-stage magnetic dipolarizations in the magnetotail, two auroral breakups of which the first occurring at lower latitudes than the second, and two consecutive Pi2-Ps6 band pulsations.