摘要
分析了2004年3月13日12:15到12:25UT期间TC-1和Cluster卫星簇的磁通门磁力计(FGM)和电子/电流试验仪(PEACE)的联合观测数据.在此期间,TC-1卫星位于日下点以南的磁层顶附近的磁鞘中,并在12:19UT左右观测到了一个典型的先正后负的磁鞘磁通量传输事件(FTE);向Cluster卫星簇位于北半球日侧高纬磁层顶附近,并于12:23UT左右穿出磁层顶进入磁鞘,且在12:21UT左右也观测到了一个典型的先正后负的磁层FTE.比较分析发现此两个FTE具有类似的磁场结构和等离子体特征,可能是同一个北向运动的FTE先后被TC-1和Cluster卫星观测到.利用Cluster 4颗卫星的多点同时观测数据,采用最小方向微分法和时空微分方法,推断Cluster卫星观测的这个FTE是尺度大小约为1.21 R_e的准二维结构,其运动方向为东北方向,与Cooling模型预测方向基本一致.利用Cooling模型的预测,推算了TC-1卫星在12:19UT观测的FTE的运动速度和尺度,进而得出随着通量管的极向运动,其速度和尺度均有所增加.
This paper analyzed the observations of the FGM and PEACE on TC-1 and Cluster Spacecraft between 12：15 and 12：25UT 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 MDD （Minimum Directional Derivative/Difference） and STD （Spatio-Temporal Difference） 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.
出处
《空间科学学报》
CAS
CSCD
北大核心
2009年第2期166-174,共9页
Chinese Journal of Space Science
基金
国家自然科学基金项目资助(40390154
40236058
40574075)
