Browsing by Author "Marshall, Andrew"

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    MMS Observations of Secondary Reconnection X-Lines and the Unexpected Phenomena Surrounding Them
    (2023-04-19) Marshall, Andrew; Reiff, Patricia
    Magnetic reconnection, the process that explosively converts energy from magnetic fields into particle thermal energy and kinetic energy, plays an important role both on the dayside an on the nightside of Earth’s magnetosphere. During periods when the interplanetary magnetic field (IMF) is southward, reconnection will occur near the subsolar point on Earth’s dayside and the neutral line on the nightside. In this work, we present one nightside event where we observed, for the first time, reconnection as part of an earthward-propagating dipolarization front (DF). Previous studies have shown current sheets in such events but never reconnection. In the second event, we discuss a dayside event with unusual wave activity in the reconnection current layer. The x-line observed in this event appears to be a secondary x-line that is moving southward while also seeing a lower hybrid drift wave (LHDW) and energy conversion due to the parallel electric field. This is the first time such wave activity has been observed at an x-line, and the energy conversion is not due to the component of the electric field that normally contributes to it. We use in-situ measurements from the magnetospheric multiscale (MMS) spacecraft, which is the first mission able to provide multipoint measurements of plasma and fields at a time resolution fast enough to observe the electron diffusion region (EDR) of reconnection. We compare these to the community coordinated modeling center (CCMC) global models of the magnetic field to help identify the expected positions of the reconnecting field lines and to determine the changes to the magnetosphere on one-minute timescales that would cause the dynamics observed at MMS’s location.