We studied the first broad band emissions, called continuum, in the dayside aurora. They are similar to Strong Thermal Emission Velocity Enhancement (STEVE) with white-, pale-pink-, or mauve-coloured light. But unlike STEVE, they follow the dayside aurora forming rays and other dynamic shapes. We used ground optical and radar observations and found evidence of heating and upwelling of both plasma and neutral air. This study provides new information on conditions for continuum emission, but its understanding will require further work.

The magnetopause represents the outer boundary of Earth's magnetosphere, protecting structures like the Van Allen radiation belts from solar wind. The magnetopause's position affects the radiation belts' behavior, causing strong and quick particle losses during geomagnetic storms. This study presents a new model to estimate the magnetopause position oriented toward drift-resolved radiation belt modeling codes.

This study investigates an ionospheric anomaly in Antarctica that affects electron concentration during summer. We analyse data from four stations, revealing different trends depending on the season and time of day. Vernadsky shows strong influence of the anomaly, while Port Stanley is less affected, and other stations do not show a clear pattern. These results highlight how local phenomena can modify global trends, providing new information about the Earth's space environment.

The electric state of the Earth’s atmosphere is manifested in the surface electric potential gradient (PG). In fair weather the PG should follow the variation of the global source of electric current in the atmosphere, called the global electric circuit. The PG is also influenced by local conditions. We use long-term series of PG and analyse PG variations during conditions of low aerosol concentrations to minimise the aerosol influence on PG obscuring its change due to the global source.

It is often the case that only magnetic field data are available for in situ planetary studies using spacecraft. Either plasma data are not available or the data resolution is limited. Nevertheless, the theory of plasma instability tells us how to interpret the magnetic field data (wave frequency) in terms of flow speed and beam velocity, generating the instability. We invent an analysis tool for Mercury's upstream waves as an example.

This study focuses on a TIMED Doppler Interferometer (TIDI)–meteor radar (MR) comparison of zonal and meridional winds and their dependence on local time and latitude. The correlation calculation between TIDI wind measurements and MR winds shows good agreement. A TIDI–MR seasonal comparison and analysis of the altitude–latitude dependence for winds are performed. TIDI reproduces the mean circulation well when compared with MRs and may be a useful lower boundary for general circulation models.

A configuration of field-aligned currents (FACs) that can explain the rapid variation in the geomagnetic field in mid-latitude Europe on 29 October 2003 was recently proposed. Interestingly, this specific system of the FACs might also explain the famous Carrington event on 2 September 1859. By analysing the declination observed in mid-latitude Europe on 29 October 2003, we confirmed an important feature of the proposed current system, the westward movement of one of the FACs.

The study makes use of magnetic field data from the closely spaced Swarm A and C spacecraft during the counter-rotating orbit phase. It allows investigating the spatial and temporal correlation lengths of small-scale and mesoscale FAC (field-aligned current) structures at auroral latitudes. Stationarity features of small-scale FACs (10–50 km scale size) are temporal length < 18 s and correlation length < 12 km. For mesoscale FACs (75–220 km scales) we obtain a stability of > 40 s and correlation length > 20 km.

Flux ropes are peculiar structures of twisted magnetic field occurring in many regions of space, near Earth and other planets, at the Sun, and in astrophysical objects. We developed a new way of detecting flux ropes in large supercomputer simulations of near-Earth space, and we use it to follow the evolution of flux ropes for long distances past the Earth in the flow direction. This will be useful in future studies as these flux ropes are involved in the transport of matter and energy in space.

Interplanetary shock waves are one of the major forms of heliospheric transients that can have a profound impact on solar wind plasma and magnetic field conditions and accelerate charged particles to high energies. This work performs an extensive statistical analysis to detail how some of the key solar wind turbulence parameters, critical for understanding particle acceleration, are modified by the interplanetary shocks waves.

Traveling ionospheric disturbances are plasma density fluctuations usually driven by atmospheric gravity waves in the neutral atmosphere. The aim of this study is to attribute multi-instrument observations of traveling ionospheric disturbances to gravity waves generated in the upper atmosphere at high latitudes or gravity waves generated by tropospheric weather systems at midlatitudes.

This study explores the influence of temperature anisotropy and kappa-distributed suprathermal particles on electromagnetic ion cyclotron (EMIC) wave propagation in a multi-ion magnetospheric plasma. Results show that higher anisotropy enhances wave growth, while an increasing kappa value suppresses it, leading to thermalization. These findings have key implications for radiation belt electron loss and space weather modeling. Future work should incorporate nonlinear effects and observational validation.

In this work, the investigation of Rossby-Khantadze waves with sheared zonal flows in E-ionosphere is presented. The spatially inhomogeneous Earth's angular velocity and background magnetic field are considered. The field inhomogeneity makes the coupling of Rossby and Khantadze waves. The numerical work of obtained linear frequencies is done. By using the method of multiple scale, we obtained a new Boussinesq nonlinear equation. Also, we obtain the travelling solitary structures.

We use NO column density data from the Syowa station in Antarctica from 2012–2017. We compare these ground-based radiometer observations with results from a global atmosphere model to understand the year-to-year and day-to-day variability, shortcomings of current electron forcing, and how geomagnetic storms are driving the variability of NO. Our results demonstrate an underestimation in the magnitude of day-to-day variability in simulations, which calls for improved electron forcing in models.

Our study probes how solar-wind disturbances affect cosmic rays on Earth during solar eruptions. Increased cosmic rays during heightened solar wind suggest that turbulence scatters and redistributes them, prolonging intensity. Understanding these effects is crucial for accurate cosmic-ray data interpretation.

This research explores how hydrogen ions and oxygen ions move and gain energy in Earth’s magnetosphere at high altitudes and latitudes. Using Monte Carlo simulations, predictions of mean particle theory, and corresponding observations, we compared different energy profiles of hydrogen and oxygen ions across polar-wind, aurora, cusp, and central-polar-cap regions. Our findings reveal that unique interactions in each area affect energy gain differently, with implications for future space weather models.

Analysis of 10 years of continuous measurements provided MMARIA/SIMONe Norway and MMARIA/SIMONe Germany reveals that the divergent and vortical motions in the mesosphere and lower thermosphere exchange the dominant role depending on the height and the time of the year. At summer mesopause altitudes over middle latitudes, the horizontal divergence and the relative vorticity contribute approximately the same, indicating an energetic balance between mesoscale divergent and vortical motions.

The magnetic mirror force bends the orbits of electrons precipitating into the atmosphere. It has been suggested that relativistic electrons make much less ionization due to the force than if it did not exist, but the actual effectivity in the atmospheric electron density has not been revealed. We used conjugated observational data from the ELFIN (Electron Losses and Fields INvestigation) satellite and the EISCAT (European Incoherent SCATter scientific radar system) Tromsø radar to find that the electron density decreased by about 40 % at 80 km altitude because of the force.

This study addresses the design of next-generation incoherent scatter radar experiments used to study the ionosphere, particularly with systems that have multiple sites. We have developed a method to estimate uncertainties of measurements of plasma density, temperature, and ion drift. Our method is open-source, and helps to optimize radar configurations and assess the effectiveness of an experiment. This method ultimately serves to enhance our understanding of Earth's space environment.

The lack of ground observation instruments and the vast ocean coverage make the Southwest Indian Ocean (SWIO) region difficult to access and poorly studied. For gathering ground-based camera information, satellite measurements have been used with the primary goal of characterizing both sites Saint-Denis of Reunion Island and Antananarivo Madagascar in terms of cloudiness. This study shows the particularity of each site and enhances our understanding of cloud properties, particularly in the SWIO.

By using magnetic field recordings sampled at 50 Hz by Swarm A and C satellites around the quasi-coplanar orbit configuration, near 1 October 2021, we investigate the properties of kilometer-scale field-aligned currents (FACs) at auroral latitudes. The kilometer-scale (0.2-5 km) FACs exhibit short-lived (<1 s) randomly appearing large current density spikes (partly exceeding 100 µA m-2). Preferred occurrences are the noon to prenoon (nightside to dusk) sector around 80° (70°) MLat, respectively.

Space weather can cause electric currents to flow through the ground at the Earth’s surface. These currents correspond closely to the rate of change of the magnetic field, following Faraday’s law of induction. The scientific community regularly uses two different methods to calculate the rate of change of the magnetic field for this purpose. We show that there is a large difference between the two methods, and highlight certain situations where this difference is potentially significant.

This study uses images taken by the Swedish satellite MATS (Mesospheric Airglow Tomography and Spectroscopy) to conduct a statistical analysis of the molecular oxygen atmospheric band emissions in the aurora. This auroral emission can not be observed from the ground, making it one of the least understood auroral emissions. Our results provide a new dataset with information on the peak altitude, geomagnetic location, and auroral intensity of 378 events detected between February and April 2023.

Plasma convection is the movement of plasma that drags the magnetic field lines with it. Magnetic field in the solar wind interacts with the Earth's magnetic field and drags the dayside field lines of the Earth's magnetosphere toward nightside, causing the plasma inside the magnetosphere to circulate around the Earth in a process called the Dungey Cycle. Our simulation and methodology desribe this cycle in detail and find features in the convection that are not explained by fluid models.

This study investigates the ionospheric signatures of a Bursty Bulk Flow in Earth’s magnetotail using a global 6D hybrid-Vlasov simulation coupled with an ionospheric model. The results show that a reconnection-driven Bursty Bulk Flow generates vortices that produce field-aligned currents, which map to the ionosphere with a distinct east–west orientation and exhibit a characteristic westward drift. Variations in ionospheric observables are identified as clear signatures of this flow.

We studied how solar eclipses affect the electric field in the atmosphere and the movement of charged particles above Earth near the magnetic equator. Using ground-based instruments in Peru, we found that eclipses can lead to significant changes, depending on weather conditions. These results help us better understand how solar events influence the near-Earth environment and its connection to the upper atmosphere.

Key properties of the ionospheric electrodynamics are electric fields, currents, and conductances. They provide a window to the vast and distant near-Earth space, cause Joule heating that affect satellite orbits, and drive geomagnetically induced currents (GICs) in technological conductor networks. We have developed a new method for solving the key properties of ionospheric electrodynamics from ground-based magnetic field observations.

Space plasmas often deviate from the usual thermal pattern assumed in standard models. Using the modified Kappa distribution, we derived how this non-standard energy spread alters electrical flow, heat transfer, and particle motion. We found that stronger deviations increase collision rates and weaken transport coefficients, while normal behaviour returns in the thermal limit, improving our insight into space environments.

The ionosphere is where Earth’s atmosphere overlaps with a gas of charged particles in space. There, collisions with neutral air and electromagnetic forces driven by the solar wind control plasma motion. We created a global model that includes magnetic induction, explaining how electric currents and fields change, offering a more accurate view of atmosphere–space coupling than conventional models based on electric circuits.

We applied machine learning to investigate how the solar wind and Earth's geomagnetic activity control the position of the magnetopause, the boundary layer of Earth's magnetic field. Our results demonstrate that geomagnetic activity strongly influences this boundary and should be incorporated in predictive models. Using data from multiple spacecraft, we developed a simple mathematical description of the magnetopause distance that improves understanding of solar wind–magnetosphere interactions.

Heliophysics spans a wide range of disciplines covering the study of the Sun and the different Solar System bodies, such as Earth and other planets, moons, comets, and asteroids, and their interactions with the Sun, focusing on plasma and atmospheric processes. A grass-roots effort has been recently started toward establishing a European Heliophysics Community (https://www.heliophysics.eu/). This white paper outlines the motivation, priorities, and a future vision of Heliophysics in Europe.