A Conjugate Study of ULF Waves at the Cusp: A GEM Project

这是一种在共轭半球尖峰站研究极低频波谱的建议。位于北半球斯瓦尔巴群岛朗伊尔城的一个极光观测站已经运行了近十年，它配备了感应线圈和磁通门磁力计来测量极低频波谱。该站还配备了全天和子午线扫描光度计，为磁测量提供了光学背景。在南半球，位于南极洲戴维斯的澳大利亚站也配备了感应线圈和磁通门磁力计，并对与尖峰有关的极低频波谱进行了数年的观测。我们已经开始交换数据，分析显示出有希望的相关性。众所周知，尖端区域是一个丰富的ULF波的来源，横跨从近直流电到赫兹以上的频谱。频谱由波和变化的集合组成，其原因包括低频端的边界运动和宏观边界不稳定性，以及中频与太阳风相关的脉冲和相干信号，在磁层边界层附近的不稳定等离子体和激波尖等离子体中产生的超离子回旋波。我们的分析工作得到了地球物理研究所等离子体模拟小组的协助。我们的目标是在一个战役的基础上收集两个地点的ULF数据，以便：调查这些地点尖端的共轭性；O识别与尖端相关的波浪产生机制；o检查两个地点的极低频光谱的相关性；O识别磁层顶通量传递和粒子注入的特征；O使用波作为边界位置的诊断。

This is a proposal to study the ULF wave spectrum at cusp stations in conjugate hemispheres. An auroral observatory located at Longyearbyen, Svalbard in the northern hemisphere has been in operation for nearly a decade and is equipped with induction coil and fluxgate magnetometers to measure the ULF wave spectrum. The station is also instrumented with all-sky and meridian scanning photometers which provide an optical context for the magnetic measurements. In the southern hemisphere, the Australian station at Davis, Antarctica is also equipped with induction coil and fluxgate magnetometers and has made observations of the ULF wave spectrum associated with the cusp for several year. We have begun an echange of data and the analysis shows promising correlations. It is well known that the cusp region is a rich source of ULF waves spanning the frequency spectrum from near dc to above Hz. The spectrum consists of an ensemble of waves and variations with causes ranging from boundary motions and macroscopic boundary instabilities at the low frequency end, through impulsive and coherent signals with correlation to the solar wind at intermediate frequencies, up to an beyond ion-cyclotron waves generated in the unstable plasma near the magnetospheric boundary layers and shocked cusp plasma. Our work in this analysis is aided by through collaboration with the plasma simulation group at the Geophysical Institute. Our goal is to collect ULF data at the two sites on a campaign basis in order to: o investigate the conjugacy of the cusp at these sites; o identify wave generation mechanisms associated with the cusp; o inspect the ULF spectrum at the two sites for correlations; o identify signatures of flux transfer and particle injection at the magnetopause; o use the waves as a diagnostic for location of the boundaries.