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.

Auroral precipitation refers to energetic particles that come down into the upper part of our atmosphere, the ionosphere. There, they collide with atoms and molecules and transfer some of their energy, causing aurora. The most rapid time-variation of this energy deposition and its consequences on the ionosphere are not fully understood. We show here that one can use a new model to study auroral precipitation on sub-second timescales and advance our understanding about small-scale dynamic aurora.

By utilizing the 50 Hz magnetic field recordings from Swarm A and C during the two weeks around the quasi-coplanar orbit configuration on 1 October 2021, we investigate the properties of kilometer-scale field-aligned currents at auroral latitudes. It is found that the kilometer-scale (0.3–5 km) field-aligned currents exhibit short-lived (<1 s) randomly appearing large current spikes. They are confined to certain latitude ranges, which depend on local time.

Several errors, which affect the results, are identified in this reference (Ann. Geophysicae, 30, 1051–1054, (2012)). We are interested in the present work to correct these errors.

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 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.

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.

Increases in middle atmospheric water vapour from the 2022 Hunga eruption have been measured worldwide. This study uses remote sensing measurements at two latitudes and accurate radiative transfer modeling to show significant long-wave heating effects. Though minimal at the surface, the water vapour enhancement can alter middle-atmospheric dynamics, potentially affecting ozone chemistry and weather patterns.

In this paper, we propose a new method for identifying anomalous electromagnetic phenomena in the ionosphere before and after earthquakes. This research contributes to the ongoing efforts in earthquake prediction. By analyzing satellite data from CSES-01 and applying a novel decomposition technique, we identify significant electric field disturbances prior to the May 11, 2023, Tonga Islands earthquake. We believe this work contributes to the broader understanding of seismic precursors.

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 satellite and the EISCAT Tromsø radar to find that the electron density decreased by about 40 % at 80 km altitude because of the force.

We investigate the subauroral flux maximum (at 60° North/South geomagetic) observed in low-energy particle channels. Two independent atmospheric impact measurements refute the subauroral flux under low Kp, pointing to instrumental crosstalk, likely from energetic electrons. We propose correction methods to mitigate contamination, ensuring accurate ionization estimates. Without correction, subauroral flux overestimates thermospheric ionization, underscoring the need for data refinement.

Extreme events can pose serious risks to satellites, potentially disrupting communication, navigation, and power systems. Our study estimates the worst-case radiation levels during such an event and assesses their impact on electronics and solar panels.