Extraction of the solar wind kinetic energy (∆K) by mass loading of escaping O⁺ is modelled in the exterior cusp and plasma mantle of the Earth. We found ∆K proportional to mass flux of escaping ions and square of solar wind velocity, but independent to the other parameters. The amount is sufficient to power the cusp field-aligned currents, further enhancing ion escape through Joule heating of the ionospheric ions, completing positive feedback to enhance escape with geomagnetic activities.

The question of whether mesospheric rotational population distributions of vibrationally excited OH are in equilibrium with the local kinetic temperature has been debated over several decades. We examine the relationship of multi-quantum relaxation pathways with the behavior exhibited by OH(v) rotational population distributions and find that the effective rotational temperatures of mesospheric OH(v) deviate from local thermodynamic equilibrium for all observed vibrational levels.

This work deals with the theoretical investigation of the inherent north&endash;south asymmetry in the ionospheric response to seismic infrasound. Magnetic field parallel component of the wind vector associated with the seismic infrasound varies significantly in the north–south direction due to the variation in the inclination of the Earth's magnetic field. This and other related aspects have been investigate using the physics-based ionospheric model.

The Voyager plasma observations show that the physics of the heliosheath is rather complex and that temperature derived from observation particularly differs from expectations. To explain this fact, the temperature in the heliosheath should be based on κ distributions instead of Maxwellians because the former allows for much higher temperature. Here we show an easy way to calculate the κ temperatures.

To investigate compressible plasma turbulence in the solar wind on proton kinetic scales, a high time resolution measurement of the density is obtained from the spacecraft potential. Correlation between the magnetic field strength and the density is investigated as is the rotation sense of the magnetic field. The analysis reveals that compressible fluctuations are characteristic of kinetic Alfvén waves or a mixture of kinetic Alfvén and kinetic slow waves which counter-propagate.

We performed a theoretical study of how the Earth’s ionosphere interacts with the tenuous magnetosphere above it. We asked the following: what leads to electric fields and electric currents flowing between these two regions? We concluded that one source of currents flowing between these regions is the localized heating of neutral gas by energetic particles precipitating from above (the magnetosphere).

This study used the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) and Finnish Meteorological Institute's all-sky camera. It looked at radio absorption and optical emission of the long east–west band of aurora (known as the growth phase arc), which forms at the start of substorms. The study found that radio absorption was consistently south of the bright auroral arc and that optical pulsating aurora occurs in the boundary region between the radio absorption zone and the bright arc.

An unusual geomagnetic storm effect on the ionosphere in the form of localized enhancement of total electron content southward of South Africa is investigated using data from different ionosphere sounding facilities. Global ionospheric maps allow us to get the occurrence rate of such irregularities over the period of 2002–2016 and to see its correlation with solar cycle. The events we detected occur during geomagnetic storms, but not every geomagnetic storm produces such an effect.

We present an analysis of ionospheric disturbances over China mid- and low-latitude area before and during the magnetic storm on 17 March 2015. The results show that The propagation velocity is from about 200 to 700 m s⁻¹ and the amplitude of ionospheric disturbances is from about 0.2 to 0.9 TECU min⁻¹. Moreover, the reliability of PPP solutions for static stations during the analysed period of the March 2015 storm has been found to be affected insignificantly.

Electromotive force plays a central role in the dynamo mechanism amplifying the magnetic field in turbulent plasmas and electrically conducting fluids. An algorithm is developed to measure the electromotive force using spacecraft data, and it is applied to a magnetic cloud event in interplanetary space. The electromotive force is enhanced when the magnetic cloud passes by the spacecraft, indicating local amplification of the magnetic field.

The paper presents a case study of Earth's magnetosphere dynamics during the geomagnetic storm of 14–16 November 2012. We use a recently developed global model of the magnetosphere that combines a 3-D magnetohydrodynamics model with a kinetic bounce-averaged model for a representation of the energetic ring current population (1–200 keV). We use the model together with multipoint measurements to understand the observations and provide insight into magnetosphere–ionosphere coupling aspects.

A study was conducted on the main ionospheric trough using the Electron Density Assimilative Model (EDAM). The idea was to compare results of the feature by using GPS data to results from a different method conducted in the past. The results showed that using GPS assimilated data, the feature could be modeled effectively when compared to the previous method, which shows the capability and potential of the model to study ionospheric features. This was the main purpose behind the research.

We have analyzed the low-latitude ionospheric responses to solar flares. In particular we show for the first time that 5 to 8 min of time delay is present in the peak effect in the EEJ, with respect that of S_q current outside the magnetic equator, in response to the flare radiation enhancement. We propose that the flare induced enhancement in neutral wind occurring with a time delay could be responsible for a delayed zonal electric field disturbance driving the EEJ.

Ozone and water vapor are two potent greenhouse gases in the atmosphere. They influence the temperature structure greatly, particularly in the upper troposphere and lower stratosphere. We have investigated the long-term trends in these trace gases over the Indian region using long-term data (1993–2015) constructed from multi-satellite observations. A decreasing trend in ozone associated with NO_x chemistry in the tropical middle stratosphere and a good correlation between N₂O and O₃ is found.

The longitudinal structure in geopotential heights and meridional wind is analysed for 1979–2013 in order to find its persistence and altitudinal dependence with focus on anomalous years. Substantial deviations from the average pattern are studied for Januaries – typically the second (Euro-Atlantic) peak extends to much higher altitudes than usual. The decisive role in the existence of anomalous years appears to be played by the stationary planetary wave filtering by the zonal wind pattern.

Our results suggest that sea–land interface affects the polarization parameters at coastal stations. We proposed a method for directly estimating, in the frequency domain, the normal field variations at coastal stations, by inverting the linear relationship between horizontal field measurements at coastal and reference stations. Our techniques could also be used to detect possible anomalous effects due to sporadic changes in ground conductivity.

Cross-wavelet and classical cross-correlation analyses were used in order to study solar-wind–magnetosphere coupling during HILDCAAs. Cross-correlation analyses results show that the coupling between the solar wind and the magnetosphere during HILDCAAs occurs mainly in the period ≤ 8 h. Classical correlation analysis indicates that the correlation between IMF B_z and AE may be classified as moderate (0.4–0.7) and that more than 80 % of the HILDCAAs exhibit a lag of 20–30 min.

This study aims to evaluate synergetic methods for relative humidity vertical profiling based on lidar–radiometer and lidar–simulation combinations. We demonstrate the effectiveness of combined lidar-based methods for relative humidity profiling in comparison with radiometer observations or WRF simulations and assess temperature-related uncertainties in resulting relative humidity profiles. All results are acquired during the HygrA-CD campaign in Athens (Greece) in 2014.

Transmission of powerful radio waves into the overhead ionosphere is used to study plasma turbulence processes. It is well known that the ionospheric response to radio waves is the strongest in the direction of the geomagnetic field. We have found evidence that the transmitted radio wave can propagate in a mode that enables the wave to propagate much higher in altitude and deeper into the ionosphere than what is usually expected, which may account for the strong plasma response observed.

This work presents four events of mesosphere fronts observed on King George Island, Antarctic Peninsula, in the year 2011. The atmospheric background environment was analyzed to investigate the propagation conditions for all cases. To investigate the sources for such cases, satellite images were used. In two cases, we found that strong tropospheric instabilities were potential sources, and in the other two cases, it was not possible to associate them with tropospheric sources.

This article presents characteristics of periodic waves observed in the thermosphere from airglow images collected in the Northeast of Brazil. Using simultaneous measurements of the background wind in the airglow emission altitudes, it was possible to estimate the intrinsic parameters and the role of the wind in the propagation of the waves into the thermosphere. An anisotropy in the propagation direction of the waves was observed and it could be explained by the wind filtering process.

The interaction between the magnetic field and the particles coming from outer space, which apparently have a relationship with tectonic plates, is studied. The major earthquakes of Maule (2010, 8.8 M_w), Sumatra (2004, 9.2 M_w) and Tohoku (2011, 9.0 M_w) were studied, similar frequencies being found in the vertical component of the magnetic field (microhertz range). The temporal evolution of the magnetic oscillations showed the possible link with the seismic movement of Maule in 2010.