Upstream-generated Pc3 ULF wave signatures observed near the Earth's cusp
Upstream-generated Pc3 ULF wave signatures observed near the Earth's cusp
复制标题
在地球尖端附近观察到的上游生成的 Pc3 ULF 波特征
DOI：
10.1029/2011ja017327/abstract
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Hanseup Kim
中科院分区：
文献类型：
--
作者：
T. Yeoman;D. Wright;M. Engebretson;V. Pilipenko;M. Lessard;Hanseup Kim
[1]Pc 3脉动（频率为20-100 mHz）起源于地球弓形激波上游的离子前震，这是由于反射离子和太阳风之间的相互作用，在地面脉动磁力计数据中经常观察到。以前的研究已经注意到增加的Pc 3波功率在附近的向阳面的尖点，并推断上游波获得通过尖点进入，虽然最近的研究揭示了一个更复杂的画面。在这里，我们研究Pc 3波功率在当地中午附近观察到的搜索线圈磁强计在斯瓦尔巴群岛上的三个紧密间隔的站，在一个扩展的时间间隔的HF雷达后向散射指示的尖点时，检测到的汉卡萨尔米SuperDARN雷达。然后，HF雷达尖点的赤道边缘的位置可以直接与在三个纬度处测量的Pc 3波功率进行比较，因为尖点在统计基础上跨越台站迁移。这些观测结果更符合波通过Engebretson等人（1991年a）的电离层晶体管机制沿着沿着闭合磁力线向赤道方向的尖点进入磁层，或弱耦合快波和阿尔芬波模式，然后映射到低纬度边界层或外磁层，而不是波通过尖点本身或外尖点进入磁层。
[1] Pc3 pulsations (frequency ∼20–100 mHz) which originate in the ion foreshock upstream of the Earth's bow shock due to the interaction between reflected ions and the solar wind are frequently observed in ground-based pulsation magnetometer data. Previous studies have noted increased Pc3 wave power in the vicinity of the dayside cusp and inferred that the upstream waves gained entry via the cusp, although more recent studies have revealed a more complex picture. Here, we examine Pc3 wave power near local noon observed by search coil magnetometers at three closely-spaced stations on Svalbard, during times when an extended interval of HF radar backscatter indicative of the cusp is detected by the Hankasalmi SuperDARN radar. The location of the equatorward edge of the HF radar cusp may then be directly compared with the Pc3 wave power measured at three latitudes as the cusp migrates across the stations on a statistical basis. These observations are more consistent with wave entry to the magnetosphere along closed field lines equatorward of the cusp via the ionospheric transistor mechanism of Engebretson et al. (1991a), or weakly coupled fast and Alfven wave modes, which then map to the low-latitude boundary layer or outer magnetosphere, rather than with wave entry into the magnetosphere via the cusp proper or exterior cusp.