The magnetopause is the outer boundary of the magnetosphere, which is the region around Earth where the geomagnetic field is dominant. Although the solar wind is the major driver of space weather near Earth, it cannot directly penetrate the magnetopause to enter the magnetosphere. Instead, plasma-physical processes occurring at or near the magnetopause play a key role in regulating the passage and entry of particles and energy. These processes can be (i) magnetic reconnection driving inner-magnetospheric convection, (ii) surface waves that may be amplified by the Kelvin-Helmholtz instability, or (iii) foreshock associated phenomena like hot flow anomalies, foreshock bubbles or magnetosheath jets. Changes in the solar wind conditions as well as the transient nature of these phenomena keep the magnetopause constantly in motion around an equilibrium position, where pressure balance between both sides is maintained.

This talk focuses on observations of extreme outward or inward motions of the magnetopause and their underlying causes. The observations are based on years of multi-spacecraft measurements of the Cluster, THEMIS, and MMS missions. In addition, novel approaches to modeling the magnetopause position will be discussed. These models are of particular interest for the upcoming SMILE mission, which will allow for continuous imaging of the magnetopause boundary and its motion for the first time.

recording: www.youtube.com/watch