Higher TEC day-to-day variations during the daytime than nighttime for all the years were observed. The diurnal variation shows OBS-TEC rising rapidly from a minimum just before sunrise between 03:00–05:00 LT (~ 2 TECU) in 2011, 04:00–05:00 LT (~ 3 TECU) in 2012, 03:00–05:00 LT in 2013 (~ 3 TECU), and 03:00–05:00 LT in 2014 (~3 TECU). OBS-TEC is found to increase to a broad daytime maximum between 00:12 LT 354–00:16 LT for all years before falling to a minimum after sunset.

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.