HR: 0800h
AN: SM31B-0462    [Abstracts]
TI: On the generation and topology of Flux Transfer Events
AU: * Dorelli, J C
EM: john.dorelli@unh.edu
AF: University of New Hampshire, Morse 245E 39 College Road, Durham, NH 03824, United States
AB: We investigate the generation and topology of Flux Transfer Events (FTEs) under generic southward IMF conditions. Previous research with the OpenGGCM code (Raeder, 2007) concluded that FTEs form only when the dipole tilt is nonvanishing. The Raeder FTE generation mechanism invokes a two-dimensional reconnection scenario in which the location of the stagnation point differs from that of the magnetic neutral point (owing to the dipole tilt). In the Raeder scenario, magnetosheath flow drives the formation of a new X line, producing a magnetic island which propagates northward or southward, depending on the dipole tilt. The topology of the resulting FTE is simple, consisting of a flux rope bounded by two X lines. In this work, we use the OpenGGCM code to demonstrate that in the high Lundquist number limit (i.e., when the plasma resistivity is uniformly small), FTEs can form under vanishing dipole tilt conditions. Flux ropes form spontaneously in two stages: 1) resistive tearing modifies the initially stable stagnation point flow, causing it to become unstable; 2) the stagnation point flow instability (an ideal MHD instability) results in the formation of large scale vortices which drive the formation of multiple magnetic separators. The resulting magnetic field topology becomes significantly more complex than the double X line model of Raeder (2007). We discuss some possible reasons for the discrepancy.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2724 Magnetopause and boundary layers
DE: 7859 Transport processes
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting