In this paper, quasi-empirical convective eddy diffusivity parameterizations for a coastal site are obtained. In the derivation we used Taylor's theory of statistical diffusion and sonic anemometer observations collected at 11 levels on a 140 m high tower in a convective planetary boundary layer. The test of the derived coefficients was solved by solving the equation of diffusion–advection by the fractional step/locally one-dimensional (LOD) methods.

The paper focuses on the analyses of the global occurrence of equatorial plasma bubble events using S4 data that were calculated from GPS radio occultation measurements of the FormoSat-3/COSMIC mission. The advantage in using radio occultation data is that we get information not only on the occurrence and intensity of the equatorial bubble events, but also on the altitude distribution. We analyzed a 10.5-year time series of COSMIC data and demonstrated a strong dependence on the solar cycle.

The structure and medium-scale dynamics of Earth's bow shock and how charged solar wind particles are reflected by it are studied in order to better understand space weather effects. We use advanced supercomputer simulations to model the shock and reflected ions. We find that the thickness of the shock depends on solar wind conditions but also has small-scale variations. Charged particle reflection is shown to be non-localized. Magnetic fields are important for ion reflection.

The Earth's atmosphere is constantly losing molecules and charged particles, amongst them oxygen ions or O⁺. Quantifying this loss provides information about the evolution of the atmosphere on geological timescales. In this study, we investigate the final destination of O⁺ observed with Cluster satellites in a high-altitude magnetospheric region (plasma mantle) by tracing the particles forward in time using simulations. We find that approximately 98 % of O⁺ escapes the Earth's magnetosphere.

Solar storms are natural phenomena that affect technologies on which our societies are highly dependent. The understanding of solar storms and the capability to anticipate their effects on our technologies is of main interest to shield our societies. In this work we present a semi-empirical approach to increase our understanding of solar storms when they hit our planet. Additionally, we also preset a possible pathway to forecast the transits of solar storms by our planet's orbit.

We present a comprehensive statistical study of the response of the Earth's space environment in sheath regions prior to interplanetary coronal mass ejections. The inner magnetospheric wave activity is enhanced in sheath regions, and the sheaths cause significant changes to the outer radiation belt electron fluxes over short timescales. We also show that non-geoeffective sheaths can result in a significant response.

This paper presents a comprehensive analysis of the solar event that occurred on 25 August 2018. This kind of comprehensive analysis plays a key role in better understanding the complexity of the processes occurring in the Sun–Earth system determining the geoeffectiveness of manifestations of solar activity. The analysis presented here shows for the first time a direct link between characteristics of solar perturbation, the magnetosphere–ionosphere system response and space weather effects.

The performance of the IRI-2016 model in simulating GPS-TEC is assessed based on various statistical tools during two distinct solar activity periods. In particular, the categorical metrics used in the study to assess the performance of the empirical and climatological IRI-2016 model at the margins of the TEC distribution reveal remarkable model skill in simulating the observed tails of the TEC distribution, which is much better than accurately simulating the observed climatology as designed.

During magnetic storms the magnetic disturbance at low latitudes becomes asymmetric, enhanced in the evening sector and reduced around morning. This has been attributed to the asymmetric ring current. Here a new 3D current system is proposed for explaining the asymmetric signal. Anti-sunward net currents at high latitude are connected at their noon and night ends to field-aligned currents that lead the currents to the magnetopause on the dawn and dusk flanks where the current closure occurs.

In this paper, we report on observations of frequency-banded wave emissions by ICE (Instrument Champ Électrique) on board DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions). We distinguish two components: positive and negative frequency drift rates and multiple spaced frequency bands near the magnetic equatorial plane. We show and discuss the non-free-space DEMETER frequency-banded emissions and the free-space terrestrial kilometric radiation.

The CSES observed ionospheric Pc1 waves near the wave injection regions in conjugate hemispheres during the recovery phase of the geomagnetic storm on 27 August 2018. The Pc1s were found to be Alfvén waves with mixed polarisation propagating along background magnetic lines in the ionosphere. We suggest that the possible sources of Pc1 are EMIC waves generated near the plasmapause by the outward expansion of the plasmasphere into the ring current during the recovery phase of geomagnetic storms.

Forecasting the thermosphere (atmosphere's uppermost layer from 90 to 800 km altitude) is crucial to space mission design, spacecraft operations and space surveillance. The thermosphere is controlled by the Sun through variable solar extreme-ultraviolet radiation and the solar wind. We show how the solar indices Mg II and Ap may be used in forecasting thermospheric density at 260 km, a very low altitude, where the GOCE satellite operated from 2009 to 2013, during the full rise of solar cycle 24.