Miniature flux transfer event observed at the dayside magnetopause
Abstract
Flux transfer events (FTE) have been interpreted to be the result of transient magnetic reconnection and can be observed in the vicinity of the Earth's magnetopause, as well as at other planets. FTEs are flux tubes that connect the magnetosheath to the magnetosphere, thereby allowing the transfer of particles, energy and momentum across the magnetopause. Their main signatures in satellite data are bipolar variations in the magnetic field component normal to the magnetopause, centered on an enhanced magnetic field strength. Other signatures such as pressure imbalances, bulk flow jets, and particle anisotropy distributions can be observed inside those structures. At the Earth's magnetopause, typical FTE durations range from tens of seconds to few minutes. The spatial cross section length is typically on the order of 1 Earth radii (Re). Recently, tiny FTEs were reported with cross sections of approximately 0.17 Re. In this work, we present a short time and small spatial scale FTE observed by the MMS spacecraft. The MMS probes were close to the subsolar region, on an outbound magnetopause crossing when they observed the structure. The FTE cross section length is approximately 0.05 Re, which corresponds to 5 local ion inertial lengths, and the duration was shorter than 2 seconds (as measured by the peak-to-peak bipolar signature). The large bipolar signature ( 47nT) and strong magnetic field strength (40 nT) indicate that MMS flew though the core of the FTE, while timing analysis shows that the structure was swept away with the magnetosheath plasma flow. Particles streaming along the magnetic field and a strong aligned current were observed in the FTE core. The perpendicular force is relatively smaller than the parallel force which reveals the nearly force-free nature of the FTE. We will present results from a survey of MMS FTEs on the dayside magnetopause.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSM21A2434S
- Keywords:
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- 2723 Magnetic reconnection;
- MAGNETOSPHERIC PHYSICSDE: 2724 Magnetopause and boundary layers;
- MAGNETOSPHERIC PHYSICSDE: 2728 Magnetosheath;
- MAGNETOSPHERIC PHYSICSDE: 2784 Solar wind/magnetosphere interactions;
- MAGNETOSPHERIC PHYSICS