An Isaac Newton Institute Workshop

Reconnection in the Sun and Magnetosphere (Hewlett-Packard and Spitalfields Days)

Anti-parallel merging and component reconnection: Role in magnetospheric dynamics.

Authors: Maria Kuznetsova (NASA/GSFC), Michael Hesse (NASA/GSFC), Lutz Rastaetter (NASA/GSFC), Tomas Gombosi (University of Michigan)

Abstract

Magnetic reconnection is a key process in magnetospheric dynamics. In the presence of nonzero IMF By component, magnetic neutral points are formed near the cusp region or at the flunks. The relative role of almost anti-parallel merging near neutral points vs. component reconnection at the subsolar flow stagnation point is a matter of ongoing discussions. To address this problem we employ a combination of small-scale and meso-scale MHD simulations with nongyrotropic corrections to the magnetic induction equation and global MHD simulations with adaptive mesh refinement. For high resolution meso-scale simulations we modified the ideal MHD approach by allowing the ion fluid to be nongyrotropic. We demonstrated that the reconnection rate is controlled by ion nongyrotropic behavior near the reconnection site. For small-scale geometry comparison with the results of hybrid and particle simulations will be presented. The presence of large guide field reduce ion nongyrotropy effects and slow down the reconnection rate. We will also use global MHD simulation code BATSRUS to model dayside magnetopause dynamics after IMF turning from an initial northward orientation to IMF clock angles 90 < theta < 180. Analysis of the reconnected magnetic flux budget showed that reconnection occurs along the extended area at magnetopause surface. We found that magnetopause surface become unstable and demonstrated formation of plasma bubbles and flux ropes (FTEs).