HR: 1340h
AN: SM13B-1217    [Abstracts]
TI: Separator Reconnection at the Dayside Magnetopause under Northward IMF Conditions
AU: * Dorelli, J C
EM: john.dorelli@unh.edu
AF: EOS Space Science Center University of New Hampshire, 39 College Road, Durham, NH 03824 United States
AU: Raeder, J
EM: J.Raeder@unh.edu
AF: EOS Space Science Center University of New Hampshire, 39 College Road, Durham, NH 03824 United States
AU: Bhattacharjee, A
EM: amitava.bhattacharjee@unh.edu
AF: EOS Space Science Center University of New Hampshire, 39 College Road, Durham, NH 03824 United States
AB: The physics of steady driven magnetic reconnection at the dayside terrestrial magnetopause is addressed. Three dimensional, global magnetohydrodynamics (MHD) simulations of the magnetopause are compared with analytical solutions of the resistive MHD equations corrresponding to magnetic field annihilation driven by an incompressible stagnation point flow. The simulations demonstrate that, under steady southard IMF conditions, and when the plasma resistivity is constant, reconnection occurs near the subsolar point in long, thin Sweet-Parker current sheets via a flux pileup mechanism. Since there is a finite energy in the magnetosheath available to drive the magnetic pileup (and associated fast reconnection), we expect the pileup to saturate, and the reconnection rate to drop, as the upstream plasma pressure drops to accommodate the pileup. Thus, we expect the reconnection rate to stall, the rate vanishing in the infinite Lundquist number limit. Under northward IMF conditions, and when there is a significant y component of the IMF (such that the y and z components of the IMF have comparable magnitudes), the generic magnetic field topology consists of two isolated magnetic nulls which define two separatrix surfaces (the boundaries between open, closed and IMF field lines). Magnetic reconnection (as measured by the parallel component of the magnetic field) seems to be associated with the intersection of these two surfaces, having a local maximum at the subsolar point rather than at the nulls. This configuration appears to be consistent with null-null separator reconnection (a type of component reconnection) rather than "antiparallel" merging. Implications of these results for LLBL observations under northward IMF conditions are discussed.
DE: 7835 Magnetic reconnection
DE: 7843 Numerical simulation studies
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2753 Numerical modeling
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting