Study of a global auroral Pc5 pulsation event with concurrent ULF waves
Study of a global auroral Pc5 pulsation event with concurrent ULF waves
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并发 ULF 波的全球极光 Pc5 脉动事件的研究
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
D. Sibeck
中科院分区：
文献类型：
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作者：
K. Liou;D. Sibeck
我们目前的研究结果，在极光光度（极光脉动）和磁层等离子体/磁场数据的同时，周期性变化。这一事件发生在2010年3月10日，大约13到17 UT，当时行星际磁场向南延伸，可能是由一个缓慢的冲击触发的。极地卫星上的紫外线成像仪测得的极光脉动持续时间长（约2.5小时），单色（约2.5兆赫），规模大，出现在夜间极光区，纬度范围与椭圆的纬度宽度相当。在不同的当地时间观测到的极光脉动之间没有相移，表明有一个稳定的结构。来自国防气象卫星计划特殊传感器闪烁电子和离子光谱仪的粒子数据表明，脉动是从中央等离子体片扩散。在此期间，Geotail位于黎明扇区等离子体片中，并观察到与极光脉动相同频率的ULF波，持续约35分钟。超低频波具有较大的径向分量和压缩分量，等离子体密度与总磁场呈负相关。这两个观测结果强烈表明，所观察到的超低频波与一个常设的超低频极向模式。波的压缩分量可以改变损失锥，导致周期性的极光沉淀。
We present results from a study of concurrent, periodic variations in auroral luminosity (auroral pulsations) and in magnetospheric plasma/magnetic field data. This event occurred on 10 March 2010 from ~13 to 17 UT during an extended southward interplanetary magnetic field and was probably triggered by a slow shock. The auroral pulsations, as measured by the Ultraviolet Imager on board the Polar satellite, were long lasting (~2.5 h), monochromatic (~2.5 mHz), large scale, and appeared in the night sector auroral zone with a latitudinal extent comparable to the latitudinal width of the oval. There was no phase shift between the auroral pulsations observed at different local times, indicating a stationary structure. Particle data from the Defense Meteorological Satellite Program Special Sensor Precipitating Electron and Ion Spectrometer indicate that the pulsations were diffuse originating from the central plasma sheet. During this time, Geotail was in the dawn sector plasma sheet and observed a ULF wave with the same frequency as the auroral pulsations last ~35 min. The ULF wave had large radial and compressional components, and the plasma density and total magnetic field were anticorrelated. These two observations strongly suggest that the observed ULF wave was associated with an standing ULF poloidal mode. The wave compressional component may be able to change the loss cone, resulting in periodic auroral precipitating.