Observation and simulation of flux rope structures at the dayside magnetopause

Abstract

The signatures of flux ropes with obvious core magnetic field are detected by Cluster II at the dayside magnetopause during 11: 00-11: 15 UT on Mar. 2, 2001. The similar characteristics can be found from the magnetic field variations recorded by the four spacecrafts (Cluster II C1-C4). All the three (-/+) bipolar signatures in the BN com-ponent are accompanied with enhancements of BM and mag-netic field strength B in the boundary normal coordinates (LMN coordinates). A MHD simulation with two dimensions and three components is performed to explore the reconnec-tion process driven by the incoming flow of solar wind at the dayside magnetopause. The numerical results can illustrate the recurrent formation of magnetic structures with a core magnetic field. The time history of the magnetic field B and three components Bx, By and Bz at a given point of the cur-rent sheet can reproduce the observational features of the events mentioned above.