HR: 08:15h
AN: SM11B-02    [PDF]
TI: Magnetic Reconnection and Magnetospheric Dynamics as a Function of Dipole Tilt and the IMF By Component
AU: * Park, K
EM: sun@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, 3-13 Honohara, Toyokawa, 442-8507 Japan
AU: Ogino, T
EM: ogino@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, 3-13 Honohara, Toyokawa, 442-8507 Japan
AU: Walker, R J
EM: rwalker@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, University of California, 6843 Slichter Hall, Los Angeles, CA 90095-1567 United States
AB: Magnetospheric dynamics are controlled by magnetic reconnection between the geomagnetic field and the interplanetary magnetic field (IMF). Dayside magnetic reconnection is often described by two different models: antiparallel merging which occurs preferentially where the magnetosheath magnetic field is antiparallel to the Earth_fs magnetic field and subsolar point merging which is sometimes called component merging. Observationally it is not clear which of these two models better describes the reconnection process at the magnetopause. Observations of flux transfer events (FTEs) at the dayside magnetopause are usually explained by subsolar merging, while observations of ionospheric convection are usually explained by antiparallel merging. In global magnetohydrodynamic (MHD) simulations antiparallel merging frequently dominates. A study of magnetopause reconnection as a function of IMF By and dipole tilt should help us determine which model best describes dayside merging. We have studied magnetic reconnection and magnetospheric dynamics by using a full 3-D MHD simulation for finite dipole tilt, IMF By and Bz components. We find that antiparallel reconnection is dominant at the dayside magnetopause during intervals with southward IMF, a finite IMF By component and finite dipole tilt. Under these conditions reconnection near the magnetic equator and noon-midnight meridian is suppressed because of increased magnetosheath flow. For IMF $By>0$ and finite tilt the reconnection site splits as it moves from the subsolar point. The reconnection sites separate into northern dusk and southern dawn parts for $By>0$, and the sites shift sunward in the summer hemisphere and tailward in winter hemisphere for finite tilt. There are observable changes in the ionospheric configuration that can help us determine if the antiparallel reconnection pattern in the simulation is correct. The convective flow in the ionospheric throat region where the flow changes from sunward to tailward becomes more dawnward/duskward in the summer hemisphere and more poleward in the winter hemisphere.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2753 Numerical modeling
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting