Statistical Survey of Earth’s Magnetopause Using MMS Data

The magnetopause is an important feature in near-Earth space, where the continuously emitted solar wind from the sun meets the magnetic field of the Earth. This boundary region between the so-called magnetosheath on the outside and magnetosphere on the inside is a constantly back-and-forth moving discontinuity upheld by a pressure balance on both sides, upon which an important process in mass and energy transportation through the universe called magnetic reconnection occurs. To gain further understanding about the magnetopause, this study aimed to produce additional statistical scientific material concerning the discontinuity, including the total pressure difference across it, pressure values/compositions in the magnetosheath and magnetosphere bordering it, and velocity of the magnetopause related to pressure difference. This was done by analysing data from the MMS-project during crossings of the magnetopause in late 2017 and throughout 2018 at the subsolar point and dawn-/dusk flanks. While the results show in general good agreement with previous studies, some intriguing features where noted, including a pressure difference bias towards higher mean total pressures in the magnetosheath in all regions, as well as shift in dominating pressure in the magnetosphere from magnetic pressure at the subsolar point to thermal pressure on the flanks. Further study to confirm these features ought to be conducted. Finally, no clear connection was revealed between magnetopause velocity and pressure imbalance