Magnetospheric Multiscale Mission Examination of Stress Balance in FTE-Type Flux Ropes at the Earth's Magnetopause
Abstract
Determining the magnetic field structure, electric currents, and plasma distribution within flux transfer event (FTE)-type flux ropes is critical to the understanding of their origin, evolution, and dynamics. We analyze FTEs observed by the Magnetospheric Multiscale (MMS) mission in the vicinity of the sub-solar magnetopause, i.e. 12 ± 22.5' Local Time and XGSM > 7 RE. High-resolution data from the Fluxgate Magnetometer (FGM) and Fast Plasma Investigation (FPI) are used to determine and compare the extent to which large (> 1 RE) and small (ion scale) diameter FTEs are force-free, i.e. J×B=0, or non-force-free, i.e. J×B= gradP. Three independent methods are used: i) current density parallel and perpendicular to the magnetic field derived from the plasma measurements or magnetic field using the curlometer technique; ii) direct measurement of the plasma pressure gradient by FPI; and iii) fitting magnetic field to force-free (J=αB) flux rope models. Our initial results indicate that the plasma content of the ion-scale FTEs often exceeds that of larger FTEs. This results in higher plasma pressure gradients inside smaller FTEs and a magnetic field that is less force-free than the larger flux ropes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSM32B..08A
- Keywords:
-
- 2723 Magnetic reconnection;
- MAGNETOSPHERIC PHYSICSDE: 2724 Magnetopause and boundary layers;
- MAGNETOSPHERIC PHYSICSDE: 2728 Magnetosheath;
- MAGNETOSPHERIC PHYSICSDE: 2784 Solar wind/magnetosphere interactions;
- MAGNETOSPHERIC PHYSICS