Magnetic disturbances in the vicinity of synchronous orbit and the substorm current wedge - A case study
Magnetic disturbances in the vicinity of synchronous orbit and the substorm current wedge - A case study
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同步轨道附近的磁扰动和亚暴流楔 - 案例研究
DOI：
10.1029/ja090ia10p09583
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发表时间：
1985
影响因子：
--
通讯作者：
B. Ledley
中科院分区：
文献类型：
--
作者：
H. Singer;W. Hughes;C. Gelpi;B. Ledley
先前使用中纬度空军地球物理实验室（AFGL）磁力计网络在地面观测到的π 2脉动和磁湾的一些特征已被证明与在孤立的亚暴爆发期间亚暴电流楔发展的想法一致。特别是利用AFGL网观测到的H和D分量磁湾扰动和Pi 2极化椭圆水平分量的方位角，确定了亚风暴流楔的近似中心和方位角范围。本文将此技术应用于一个明确定义的亚风暴，确定了在L≃6.6处的GOES 2和3号同步卫星以及在L≃8.1处的SCATHA卫星的亚风暴电流楔位，以解释这些卫星观测到的磁特征。我们发现，在当前楔内的两颗卫星，在当地午夜之后的位置，同时观测到从亚暴开始时开始的背景场结构的双极化；然而，在亚暴开始时经常观测到的脉冲、不规则振荡只被其中一颗卫星观测到。楔子内的另一颗卫星在3分钟的延迟后观察到类似的扰动，这可能是由于亚风暴电流楔子的下行部分的电流增强或运动。位于电流楔以西和外部的卫星在事件期间没有观察到磁场的显著变化。这些观测说明了解释单颗卫星测量亚暴效应的困难。如果只有来自楔西边卫星的磁场数据可用，那么亚暴就不会被探测到。此外，一个不正确的亚暴开始时间可能是从楔内的一个卫星中推断出来的。
Some features of Pi 2 pulsations and magnetic bays observed on the ground using the mid-latitude Air Force Geophysics Laboratory (AFGL) Magnetometer Network previously have been shown to agree with ideas concerning the development of a substorm current wedge during isolated substorm onsets. In particular, the H and D component magnetic bay perturbations and the azimuths of the horizontal component of the Pi 2 polarization ellipse observed by the AFGL Network have been used to locate the approximate center and azimuthal extent of the substorm current wedge. In this paper we apply this technique to a well-defined substorm to locate the substorm current wedge position relative to the GOES 2 and 3 synchronous satellites at L ≃ 6.6 and the nearby SCATHA satellite at L ≃ 8.1 to explain the magnetic features observed by those satellites. We find that the two satellites within the current wedge, at a position just after local midnight, simultaneously observe a dipolarization of the background field configuration beginning at the time of the substorm onset; however, the impulsive, irregular oscillations frequently observed at substorm onset are only observed by one of the satellites. The other satellite within the wedge observes a similar disturbance after a 3-minute delay which may be attributed to an intensification or movement of currents in the downward current portion of the substorm current wedge. The satellite west of and outside the current wedge observes no significant change in the magnetic field during the event. These observations illustrate the difficulties of interpreting single-satellite measurements of substorm effects. If magnetic data from only the satellite west of the wedge had been available, the substorm would have gone undetected. Furthermore, an incorrect substorm onset time could have been deduced from one of the satellites within the wedge.