A new type of wave has been detected by the magnetometer of the Rosetta spacecraft close to comet P67/Churyumov-Gerasimenko. We provide the analytical model of this wave excitation from linear perturbation theory. A modified ion-Weibel instability is identified as source of this wave excited by a cometary current. The waves predominantly grow perpendicular to this current. A fan-like phase structure results from superposing the strongest growing waves in a cometary rest frame.

The asymmetries between the leading and trailing edges of large-scale plasma density structures in the ionosphere are examined using a general formalism for the gradient-drift instability for arbitrary altitude and propagation direction. The asymmetry changes dramatically with propagation direction and is most likely to be observed by a ground-based radar when the radar’s boresight is parallel to the structure’s elongation direction and perpendicular to its direction of motion.

The Global Ionosphere Thermosphere Model has been validated against flight data. The validation shows a linear dependency of the neutral density values with respect to the solar activity. In particular, the thermosphere model shows an over-predicting or under-predicting behaviour under high or low solar activity respectively. The reasons for such behaviour can be attributed to an erroneous implementation of the chemical processes or the gas transport properties in the model.

The rigorous derivation of the Jüttner (covariant Boltzmann) distribution is provided for anisotropic pressure (or temperature) tensors. It was in similar form anticipated first by Gladd (1983). Its manifestly covariant version follows straightforwardly from its scalar property.

In the paper we study flapping wave structures, generated in the neutral plane of the Earth magnetotail. Investigated flapping is an important process of magnetosphere dynamics, connected with magnetic energy transformation and magnetic storm formation. Large separation of Cluster spacecraft allows us to estimate both local and global properties of flapping current sheets, the typical flapping times and propagation directions.

​The international reference ionosphere (IRI) model is a widely used model of the ionosphere. We compared this model with 16 years of radar measurements of electron density from Svalbard at altitudes between 200 and 500 km. Our results show that the model is biased towards an underestimation of the electron density in the high-latitude ionosphere and that this underestimation is most severe at nighttime. The model performs best at altitudes around the peak height of the electron density.​

Spacecraft-mounted magnetic field instruments (magnetometers) need to be routinely calibrated. This involves determining the magnetometer outputs in vanishing ambient magnetic fields, the so-called offsets. We introduce and test a new method to determine these offsets with high accuracy, the mirror mode method, which is complementary to existing methods. The mirror mode method should be highly beneficial to current and future magnetic field observations near Earth, other planets, and comets.

The paper presents simultaneous observations made with a radar (SOUSY) and an unmanned aerial system (DataHawk) with the propose of studying the lower troposphere with high resolution. Through the comparison of both measurements, it was possible to compute the radar calibration constant, which will help to obtain calibrated measurements of turbulent parameters of the atmosphere.

The dense horizontal sampling of atmospheric temperature profiles by the microwave limb sounder MLS on the NASA satellite AURA permit the estimation of global distributions of inertia-gravity waves (IGWs) in the middle atmosphere. We present and discuss the estimated global distributions of IGWs for July 2015 and January 2016. A dependence on the zonal wind distribution is obvious. The distributions of IGWs are a bit similar to the global distributions of small-scale gravity waves.

The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data, including the accuracy improvement of tropospheric zenith hydrostatic delay and precipitable water vapor conversion factor.

We have derived ozone and temperature responses to solar variability over a solar cycle, from 2002 to 2014 at 20–60 km and 48°S–48°N, based on a new dataset (SABER). These global results can be directly compared with 3-D models and will help in understanding not only the physical processes but also how they affect the Earth's climate. The simultaneous measurements of ozone and temperature will give added insight into the dynamics and photochemistry of the middle and upper atmosphere.

ULF waves can be generated by modulated HF heating in the ionospheric F region, which has long been considered for secure communication with submarines. In this paper we study the effects of background parameters on the process of ULF wave generation and propagation by using a numerical simulation. We find that wave radiation efficiency is higher in the daytime ionosphere at lower latitudes, while ground wave intensity is larger in the nighttime ionosphere with lower modulation frequency.

This study statistically quantifies the errors in local magnetic field directions that are derived from electron directional distributions measured by Los Alamos National Laboratory geosynchronous (LANL GEO) satellites. We demonstrate for the first time that derived magnetic field directions in GEO orbit should statistically match the real magnetic directions ~2 times better than those from a list of empirical models and have no significant dependence on magnetospheric activities.

We have investigated thrust characteristics of an electric solar wind sail (E-sail), which is a newly proposed propulsion system, by using numerical simulations. The thrust obtained from our simulation was lower than the thrust esimated by past studies. We have also developed a method to estimate the thrust of the E-sail without time-consuming particle simulations.

Pc5 pulsations are global magnetohydrodynamic events in the magnetosphere. This article details the analysis of Pc5 pulsation events observed by SuperDARN high-frequency radars within their field of view together with magnetometers. We believe that despite much theoretical knowledge, very few pulsation events observed by multiple radars have been reported in the literature to determine in detail the physical characteristics of Pc5 pulsation events by direct observation.