May 4, 2012, 12:00 pm - 1:00 pm

May 4, 12:00 pm - 1:00 pm

Relation between cusp ion structures and dayside reconnection during four different IMF clock angles

Dr. Hyun-Ju Connor, Space Science Center at University of New Hampshire

Magnetic reconnection is a key mechanism for transferring solar wind energy into the Earth's magnetosphere, causing various geomagnetic effects such as magnetic storms and substorms. However, reconnection happens on scales of a few ion or electron inertial lengths, and direct observation of reconnection is very difficult with the small number of satellites. With this restriction, scientists focus on dynamic results of reconnection which can be observed far from the reconnection sites. Dispersed ion signatures observed near the magnetosphere cusps, called cusp ion structures, have long been used to infer locations and properties of reconnection at the Earth's magnetopause. In this talk, we introduce a dynamic model of cusp ion structures using OpenGGCM 3D global MHD model and Liouville Theorem Particle Tracer, and investigate the general relation between cusp ion structures and dayside reconnection processes during four different IMF clock angles of 0°, 60°, 120°, and 180°. Our model produces a reverse dispersion, double reverse dispersions, a flat and dispersed signature, and a normal dispersion under each IMF condition. From the detailed study of the ion entry points and the reconnection patterns on the magnetopause, we find that lobe reconnection, recurring FTE formation, coexistence of component and anti-parallel reconnection, and subsolar reconnection cause those cusp structures, respectively. We also find that cusp ions during northward IMF originate from an anti-parallel reconnection zone whose shear angle is over 170°. Conversely, during southward IMF ions precipitate not only from a high shear angle zone but also from a very low shear angle zone.