Recent  

Collisional fragmentation of asteroids, comets and meteoroids is the main source of dust in the solar system. The dust distribution is however uncharted and the role of dust in the solar system is largely unknown. At present, the interplanetary medium is explored by the Solar Orbiter spacecraft. We present a novel method, based on artificial intelligence, that can be used for detecting dust impacts in Solar Orbiter observations with high accuracy, advancing the study of dust in the solar system.

Magnetopause is a shielding boundary of planetary magnetic field. Many mathematical models have been proposed to describe or to reproduce the magnetopause location, but they are restricted to the real-number functions. In this work, we analytically develop a magnetopause model in the complex-number domain, which is advantageous in deforming the magnetopause shape in a conformal (angle-preserving) way, and is suited to compare different models or map one model onto another.

The study of some ionospheric events benefit from the knowledge of how the physics varies over a volume and over time. Examples are studies of aurora or energy deposition. With EISCAT3D, measurements of ion velocity vectors in a volume will be possible for the first time. We present a technique that uses a set of such measurements to estimate electric field and neutral wind. The technique relies on adding restrictions to the estimates. We successfully consider restrictions based on physics.

We study how the polar regions of the Earth connect to space along magnetic field lines. While the Earth's magnetic field is mostly the shape of a dipole, at high latitudes the field lines tend to be open and connect to interplanetary space. This area of open field line is called the polar cap, and it is highly dynamic. Through data analysis and computer simulations, we find that the shape of the polar cap is closely controlled by the magnetic field embedded in the solar wind.

We have examined events during which the measured magnetic field on the ground changes very rapidly, causing a risk to technological conductor networks. According to our results, such events occur when strong electric currents in the ionosphere at 100 km altitude are abruptly modified by sudden compression or expansion of the magnetospheric magnetic field farther in space.

We measured the height of green and blue aurorae using thousands of camera images recorded over a 7-year period. Both colours are typically brightest at about 114 km altitude. When they peak at higher altitudes the blue aurora is usually higher than the green aurora. This information will help other studies which need an estimate of the auroral height. We used a computer model to explain our observations and to investigate how the green aurora is produced.

Magnetic holes are curious localized dropouts of magnetic field strength in the solar wind (the flow of ionized gas continuously streaming out from the sun). In this paper we show that these magnetic holes can cross the bow shock (where the solar wind brake down to subsonic velocity) and enter the region close to Earth’s magnetosphere. These structures may therefore represent a new type of non-uniform solar wind–magnetosphere interaction.

From the statistical analysis of potential plasmaspheric plume, we find that there is almost no correlation between plume width and the level of geomagnetic storm intensity. However, for plumes in the recovery phase after improved sifting, there is a negative correlation between the plume width and absolute value of minimum Dst during the storm. We suggest that the plasmaspheric particles may escape quickly during intense storms, causing plume to be relatively narrow during the recovery phase.

We observed two different wave propagations in the earth’s upper atmosphere: a gravity wave in the mesosphere and the ionospheric disturbances. We investigated the wave propagations by using airglow imaging techniques. It is found that there was a gravity wave generation from the tropospheric convection spot, and it propagated upward in the ionosphere. This reports observational evidence of gravity wave propagation from the troposphere to ionosphere.