Current Sheet Structure and Motion Observed by Cluster on September 15, 2001
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摘要: 2001年9月15日0430-0515 UT期间,Cluster卫星多次穿越磁尾电流片.由FGM、CIS等仪器获得了电流片磁场,粒子速度等数据变化情况,并得到了磁尾高速流的两次明显反转.本文采用GSM坐标系.利用求磁场空间梯度张量的方法获得了越尾电流,其电流密度的峰值为28nA/m2.并对电流片在垂直方向上的摆动和在晨昏方向的波动现象进行了分析.数据显示此时电流片为薄电流片并有一个变薄的趋势,其厚度大约为0.2-0.3 Re.磁场重联时地向流与尾向流均超过了1000 km/s,并测得了电流片的法线方向和运动速度,从而得到了磁尾电流片的结构和运动情况.Abstract: Multiple crossings of the neutral sheet were observed by the Fltax Gate Magnetometer (FGM) and the Cluster Ion Spectrometry experiment (CIS) onboard the Cluster li at (-19, 4,-1) Re from 0430 UT to 0515 UT on September 15, 2001. The high-speed proton flow, which reversed from tailward to Earthward, was detected during the multi-crossings. Using a linear gradient/curl estimator technique the cross-tail current was obtained. The peak of the current density reached 28 nA/m^2. A large-scale wave propagating duskward and the thin current sheet flapping in the vertical direction were investigated, the thickness of the current sheet ranged from 0.3 Re to 0.2 Re, and had a tendency of being thinner. The velocity of the proton bulk flow in the x direction exceeded 1000 km/s during the magnetic field reconnection. By using the multi-point timing analysis and Minimum Variance Analysis, the structure and motion of the magnetotail current sheet were estimated.
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Key words:
- Current sheet /
- Cluster /
- Magnetic field reconnection /
- Current sheet flapping
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