HR: 11:40h
AN: SM32A-05 INVITED     [Abstracts]
TI: Flux Pileup Reconnection at the Dayside Magnetopause under Northward IMF Conditions
AU: * Dorelli, J C
EM: john.dorelli@unh.edu
AF: UNH EOS Space Science Center, 245E Morse Hall 39 College Road, Durham, NH 03824 United States
AU: Bhattacharjee, A
EM: amitava.bhattacharjee@unh.edu
AF: UNH EOS Space Science Center, 245E Morse Hall 39 College Road, Durham, NH 03824 United States
AU: Raeder, J
EM: J.Raeder@unh.edu
AF: UNH EOS Space Science Center, 245E Morse Hall 39 College Road, Durham, NH 03824 United States
AB: An unsolved problem in magnetospheric physics concerns the geometry of magnetic reconnection at the dayside magnetopause under generic northward interplanetary magnetic field (IMF) conditions. There are currently two popular and competing models which address this problem. In the "antiparallel" reconnection model, the reconnection line is the locus of points on the magnetopause surface for which the magnetosheath and magnetospheric fields are antiparallel. In contrast, the "component" reconnection model does not constrain the reconnecting fields to be antiparallel, instead identifying the X line direction with that of the local current density. In this presentation, we argue that both of these pictures result from an inappropriate application of ideas from two dimensional reconnection theory to an inherently three dimensional situation. Using global magnetohydrodynamics (MHD) simulations, we demonstrate that, in the context of resistive MHD with constant Lundquist number -- and under generic northward IMF conditions, where the y and z components of the magnetic field (in Solar Magnetospheric coordinates) are comparable -- magnetic reconnection occurs at the subsolar magnetopause via a flux pileup mechanism. Current density is distributed across the dayside magnetopause in a "ribbon" which terminates near two cusp magnetic nulls. Due to the inherently three-dimensional nature of the reconnection geometry, neither the component nor the antiparallel model is relevant; instead, the geometry is more reminiscent of "separator" reconnection, which combines aspects of both component and antiparallel merging. We discuss the possibility of using spacecraft data to test the predictions of the MHD simulations.
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2753 Numerical modeling
DE: 7835 Magnetic reconnection
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly