From L1 to the Ground: Global Magnetospheric Dynamics

From the Sun a constant stream of charged particles (mainly electrons, protons and alpha-particles) with an embedded magnetic field is emitted: the so-called solar wind. The Earth, with its own magnetic field, is acting as an obstacle in the wind. The interaction with the solar wind creates different boundaries and regions around the Earth. As seen from the Sun, there is first the bow shock, where the supersonic solar wind is braked to subsonic speed in a region called the magnetosheath. Closer to the Earth there is the magnetopause, the location where the ram-pressure of the solar wind is equal to the pressure of the compressed Earth magnetic field. Changes in the solar wind will lead to changes in the magnetic surroundings of the Earth. Whilst relatively small changes can lead to beautiful aurorae, strong changes could have disastrous effects on infrastructure on the ground and damage near-Earth satellites. In this project we will look at certain types of changes in the solar wind and their effects on the magnetic environment of the Earth. Using satellites that are monitoring the solar wind at a point between the Earth and the Sun we get information about what kind of structures are moving towards Earth. This can be a strong rotation of the magnetic field or a pressure pulse. With a large fleet of satellites flying around the Earth we can measure the changes in the field as these structures reach the Earth, and see the large- scale effect. This, combined with measurements on the ground, with magnetometers, radars and auroral cameras we can obtain a global view of the response of the Earths magnetic field to changes in the solar wind. In 2025 the ESA/CAS mission SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) will be launched, which will observe the Earths magnetosphere in soft X-ray and UV radiation. In order to understand the observations of this mission it is of great importance that we know how, statistically, the Earths magnetosphere behaves when it responds to structures in the solar wind. Therefore, the project will deliver statistical studies of the interaction with the three most common structures: rotations of the interplanetary field, coronal mass ejections and strongly increased solar wind pressure. This project will deliver statistical information for space weather and its hazards for satellites and ground infrastructure and a guide for the interpretation of the data from a new space mission.