In this investigation a statistical analysis of the characteristics of mesospheric inversion layers (MILs) over tropical regions is presented. This study involves the analysis of 16 years of lidar observations recorded at Reunion (20.8° S, 55.5° E) and 21 years of lidar observations recorded at Mauna Loa (19.5° N, 155.6° W) together with SABER observations at these two locations. Results presented in this study confirm that SAO contributes to the formation of MILs over the tropical region.

Solar activity and climate show correlations over a wide range of timescales. It is important to understand the behavior of the 27-day solar rotational period in lightning activities because it provides an opportunity to understand how the sun influences weather and climate. We analyzed lightning data extracted from diaries written in Kyoto, Japan from the mid-17th to the mid-18th century. Lightning shows the signal of the 27-day period; however, it disappeared during the Maunder Minimum.

In this study we analyzed ~ 17 years of GPS data from receivers installed in the observatory of Cachoeira Paulista, Brazil. We statistically analyzed the occurrence of GPS signal amplitude fluctuations caused by irregularities in the Earth's upper atmosphere. These signal fluctuations are known to provoke positional errors for GPS users. The results revealed that the secular variations in the Earth’s magnetic field are affecting the climatology of such GPS signal fluctuations.

This paper analyzes the influence of the recent deep and prolonged solar minimum on the daytime zonal and vertical plasma drift velocities during quiet time over Jicamarca, Peru. Our results show that an anomalously low zonal wind was mainly responsible for the observed anomalous behavior in the zonal drift followed by a decrease in the E-region conductivity and the dynamo electric field during 2008.

On the high-potential side of a double layer, elementary radiation events are detected. They occur substantially above the local electron gyrofrequency and are associated with the presence of electron holes. The velocity of these nonlinear structures can be derived from the Doppler-shifted frequency spectrum above the electron gyrofrequency. The generated electron holes appear as the nonlinear evolution of electrostatic waves generated by the electron–electron two-stream instability.

This is the first study considering ionospheric currents (both field-aligned current and Hall current) derived from high-resolution magnetic field data of the Swarm constellation in both hemispheres. The prominent auroral electrojets are found to be closely controlled by the solar wind input, but we find no dependence of their intensity on the IMF B_y orientation. An important finding is that all the IMF B_y dependences of FACs and Hall currents practically disappear in the dark winter hemisphere.

Much like solar flares, substorms occurring within the Earth's magnetic domain are explosive events that cause vivid auroral displays. A decades-long debate exists to explain the substorm onset. We devise a simulation encompassing the entire near-Earth space and demonstrate that detailed modelling of magnetic reconnection explains the central substorm observations. Our results help to understand the unpredictable substorm process, which will significantly improve space weather forecasts.

We aim to understand the link between the Sun's atmosphere, the corona, and the constant stream of plasma which escapes it, the solar wind. To do so we test how similar energetic electrons in the solar wind are to their earlier state in the corona, using oxygen ionisation states as a proxy. We find only a very weak link which varies with the type of solar wind stream and the 11-year solar cycle. We find minor evidence to suggest that this is due to solar wind processing during its outward flow.

The reconnection efficiency of the solar-wind-magnetized planet interaction depends on the conditions in the magnetized plasma flow passing the planet. When the reconnection efficiency is very low, the interplanetary magnetic field does not penetrate the magnetosphere. We study this issue for Saturn using Cassini magnetometer data, images of Saturn's aurora obtained by the HST, and the paraboloid model of Saturn's magnetospheric magnetic field. We conclude that the open model is preferable.

The total electron content (TEC) is being extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. The TEC presents significant changes during geomagnetic disturbed periods, causing degradation of signals in navigation systems and satellite communication. The geomagnetically disturbed periods occur due to enhanced solar activity and we show that the TEC presents intensifications not only during geomagnetic storms but also during HILDCAA events.

The Earth's atmosphere is constantly losing ions and in particular oxygen ions. This phenomenon is important to understand the atmospheric evolution on a large timescale. In this study, the O⁺ outflow is estimated during six extreme geomagnetic storms using the European Cluster mission data. These estimations are compared with average magnetospheric conditions and show that during those six extreme storms, the O⁺ outflow is approximately 2 orders of magnitude higher.

Poynting's theorem provides a way to determine the spectrum of the dissipation function in magnetic turbulence. It is shown that it includes all contributions of the mechanical part of turbulence. Application to solar wind data identifies the inertial range as a state of self-organization and brings the Taylor hypothesis into question.

The evolution of the convective boundary layer (CBL) directly affects the day-to-day activity of living things by controlling the transport of pollutants, anthropogenic emissions, and moisture. During summer monsoon season cloudiness prevails over the Indian region. We found that the CBL is shallower during cloudy days compared to clear-sky days, whereas cloud at the CBL elevates its height. Thus, occurrence of cloud plays an important role in the day-to-day variation in the CBL height.