Further Study of Multiple Flux Rope Events at the Magnetopause Observed by TC‐1 on 18 March, 2004

Abstract

AbstractFrom 23:10 to 23:50 UT on 18 March 2004, the Double Star TC‐1 spacecraft detected nine flux ropes at the outbound crossing of the southern dawnside magnetopause. During this time period the Cluster constellation was staying in the magnetosheath. The four spacecraft observed that the interplanetary magnetic field (IMF) showed a dominant negative BY component together with a southward BZ. Notable guide field was found inside all nine magnetic flux ropes detected by TC‐1. The first seven ropes during 23:14~23:27 UT appeared quasi‐periodically with a repeated period about 1–4 minutes, which is much shorter than the averaged occurrence period (about 8~11 minutes) of the flux transfer events (FTEs) at the dayside magnetopause. The Minimum Variation Analysis (MVA) and the Grad‐Shafronov Reconstruction (GSR) technique are applied in present study of the multiple flux rope events. By and large, all the principal axes of flux ropes are along the dawn‐dusk direction. The deHoffmann‐Teller (HT) analysis shows that the HT velocities (VHT) of these flux ropes were all directed dawnward and poleward, indicating that they came from the duskward and equatorward side of the spacecraft location and were produced via component magnetic reconnection in the subsolar region at the magnetopause.