Recent  

The study uses SABER data to analyze the MIL phenomenon and its causative gravity wave potential energy and instability. The upper MLT inversion frequency is below 40 %, while lower inversions are below 20 %. The high potential energy (~100 J/kg) of gravity waves in the upper MLT region (85 and 90 km) is due to instability, causing large inversion phenomena. while the reverse is true in the lower MLT regions.

Auroral imaging produces large amounts of image data that can no longer be analysed by visual inspection. Thus, every step towards automatic analysis tools is crucial. Previously supervised learning methods have been used in auroral physics, with a human expert provided ground truth. However, this ground truth is debatable. We present an unsupervised learning method, which shows promising results in detecting auroral breakups in the all-sky image data.

We present by simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized-aurora computed tomography (G-ACT) method to modelled multiple auroral images and ionospheric electron density data. It is demonstrated that the G-ACT provides better reconstruction results than the normal ACT and can interpolate ionospheric electron density at a much higher spatial resolution than observed by EISCAT_3D radar.

A large explosion happened in Beirut on 4 Aug 2020, releasing significant amount of energy into the Earth's upper atmosphere; and traveling ionospheric disturbances (TIDs) were generated. The TIDs have been observed in previous studies using GPS TEC measurements around Beirut (distance < 500 km). Here we used measurements from DMSP spacecraft and ionosondes in the Mediterranean to show that the TIDs from the Beirut explosion was actually able to reach greater distance than previously reported.

Auroral spirals known as northern lights are a spectacular light show in the polar night sky. Internal processes in the polar ionosphere initiate northern lights by producing charge separations along the field lines. Parallel electric fields generated above the ionosphere by charge separations are steady-state electric fields. They occasionally discharge to produce northern lights, analogous to lightning flash in a thunderstorm.

We investigated a subauroral particle flux maximum (located at 60 N/S with focus at 0–100 E) seen in the NOAA POES detector, which we attributed to crosstalk contamination of radiation belt electrons. Affected are the processed TED proton channels (which should already be corrected by NOAA) and lower MEPED channels. The particle flux in the contaminated area can be more than factor 2 higher than typical auroral flux. The region of intense particle crosstalk may be removed by a latitudinal cut.

Long-term change in the ionosphere are expected due to increase in greenhouse gases in the lower atmosphere. Empirical formulae are used to estimate height. Through comparison with independent data we show that there are seasonal and long-term biases introduced by the empirical model. We conclude that estimates of long-term changes in ionospheric height need to account for these biases.

The solar wind is organised to slow and fast streams, interaction regions and transient structures originating from solar eruptions. Their internal characteristics are not well understood. The more comprehensive understanding of such features can give insight on physical processes governing their formation and evolution. Using tools from information theory we find that the solar wind shows universal turbulent properties on smaller scales while on larger-scale clear differences arise. 

In detailed space plasma simulations, finding and characterizing magnetic reconnection sites and related geometries requires new tools to describe complex and dynamic geometries. This paper addresses the problem by determining suitable local coordinate systems and finding the geometrical signatures of relevant magnetic field features in these coordinates. We demonstrate the utility of the method on a state-of-the-art 3D simulation of Earth's magnetosphere, performed with the Vlasiator code.

Multiple spacecraft could operate jointly to detect quantities that is unattainable by a single spacecraft. Present constellations typically consist of four spacecraft, and it is established that a planar distribution of the spacecraft should be avoided. This study addresses the configuration problem for future missions of more spacecraft to measure physical gradients of higher orders. As for quadratic gradients, spacecraft must not be on any quadric surface, such as a sphere or a cylinder.

In the magnetosheath, a near-Earth region of space, we observe increases in plasma velocity and density called jets. As they propagate, the jets disturb the ambient plasma. We study this interaction with three spacecraft simultaneously. Using the plasma motion, we reconstruct the propagation axis and calculate a simple model of the jet shape. We find that the cross section perpendicular to the propagation and the dynamic pressure decrease from the center of the jet to the rear.