Simultaneous TC-1 and Cluster Observations of FTE on 13 March 2004

This paper analyzed the observations of the FGM and PEACE on TC-1 and Cluster Spacecraft between 12:15 and 12:25 UT on 13 March 2004. In this interval, the TC-1 spacecraft located in the magnetosheath southward the sub-solar magnetopause, and observed a standard magnetosheath FTE with a positive to negative bipolar characters at about 12:19 UT. The Cluster spacecraft array was encountering the plasma boundary layer near the high-latitude magnetopause in the northern hemisphere, crossing the magnetopause into the magnetosheath at about 12:23 UT. It also observed a standard magnetospheric FTE with a positive to negative bipolar characters at about 12:21 UT. With the similar features of the magnetic field structures and plasma data, these two FTE might be the same FTE moving through TC-1 and then Cluster. Since all 4 Cluster spacecrafts observed the FTE, the four-spacecraft techniques Minimum Directional Derivative/Difference (MDD) and Spatio-Temporal Difference (STD) were applied to calculate the dimension, motion and scale of these FTE. The inferred northwardly reconnected flux tube for the FTE is shown to move north-east and tailward with a quasi-2D structure and a scale of 1.21 Re. Whilst, the FTE motions are shown to be consistent with the expected motion of reconnected magnetic flux tubes over the surface of the magnetopause, arising from a predominantly low-latitude reconnection site during the prevailing upstream conditions. According to the predictions of the Cooling model, the motion of the FTE observed by TC-1 spacecraft is inferred, which implied that the speed and size of flux tube increase with its poleward moving.