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Stephen Fuselier: The location, length, orientation, and stability of magnetic reconnection X-lines at the Earth’s magnetopause

Magnetic reconnection is the primary process of transfer of mass, energy, and momentum into the Earth’s magnetosphere. Reconnection occurs at the magnetopause, the pressure-equilibrium boundary between the shocked solar wind in the magnetosheath and the Earth’s magnetosphere. This process ultimately determines the effectiveness of the solar wind on space weather in the near-Earth environment.

Reconnection in space plasmas is inherently a cross-scale process, with coupling from the electron micro-scale of the order of 1 km to the global scale of the order of hundreds of thousands of km. At the micro-scale, electrons become demagnetized and magnetic field lines “break” and reconnect. At the global scale, this micro-scale process occurs along continuous X-lines that are many thousands of km long. Study of global scale properties of reconnection, like those described in this talk, illuminate the physics at other scales down to the micro-scale.

In this talk, the locations of magnetic reconnection X-lines at the Earth’s magnetopause are explored using observations from the magnetopause and the Earth’s magnetospheric cusps. An empirical model for the location of these X-lines is introduced. Once the location is established, evidence for long reconnection X-lines is provided, the stability of these X-lines over long timescales is discussed, and new results on the orientations of the X-lines is provided. The talk concludes with future research on X-lines at the Earth’s magnetopause.