Optical, radar, and magnetic observations of magnetosheath plasma capture during a positive IMF Bz impulse
Optical, radar, and magnetic observations of magnetosheath plasma capture during a positive IMF Bz impulse
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DOI：
10.5194/angeo-26-517-2008
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发表时间：
2008-03
影响因子：
1.9
通讯作者：
V. Safargaleev;A. Kozlovsky;T. Sergienko;T. Yeoman;M. Uspensky;D. Wright;H. Nilsson;T. Turunen;A. Kotikov
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文献类型：
--
作者：
V. Safargaleev;A. Kozlovsky;T. Sergienko;T. Yeoman;M. Uspensky;D. Wright;H. Nilsson;T. Turunen;A. Kotikov
我们提出了一项多仪器研究电离层对IMF向北转向的反应。这些观测是在斯瓦尔巴群岛近中午（11时）时段（75时）进行的。数据集包括极光观测、EISCAT和CUTLASS雷达获得的电离层流、高频雷达后向散射光谱宽度、DMSP F13卫星的粒子降水和等离子体流数据，以及感应磁力计观测到的Pc1频段脉动。利用信号到达的仰角和电离层等离子体密度剖面，用射线追踪程序定位的高频雷达后向散射对所有观测结果进行了仔细的搭配。在IMF向北转之前，分别在封闭的llbl的极地边界、llbl内部和llbl的赤道部分观测到三个极光弧。向北的国际货币基金组织转向伴随着高频雷达回波增强，其宽多普勒频谱与弧同时存在。极光弧向极地方向移动，背向散射区向相反方向移动，这与北向的磁鞘等离子体捕获和尖峰外的侦查相一致。局部地，Pc1频段的磁噪声增强与反常雷达后向散射同时发生，而在较远的磁观测站没有这种信号表明Pc1湍流的局地产生，与雷达后向散射同时发生。最后，我们讨论了可能由有限的观测数据引起的解释误差。
We present a multi-instrument study of the iono- spheric response to a northward turning of the IMF. The ob- servations were made in the near-noon (11:00 MLT) sector on Svalbard (at 75 MLAT). The data set includes auroral observations, ionospheric flows obtained from the EISCAT and CUTLASS radars, the spectral width of the HF radar backscatter, particle precipitation and plasma flow data from the DMSP F13 satellite, and Pc1 frequency band pulsations observed by induction magnetometers. Careful collocation of all the observations has been made with the HF radar backscatter located by a ray-tracing procedure utilizing the elevation angle of arrival of the signals and an ionospheric plasma density profile. Prior to IMF turning northward, three auroral arcs were observed at the poleward boundary of the closed llbl, inside the llbl, and in the equatorward part of the llbl, respectively. The northward IMF turning was accom- panied by enhanced HF radar returns with a broad Doppler spectrum collocated with the arcs. The auroral arcs shifted poleward whereas the backscatter region moved in the oppo- site direction, which is consistent, respectively, with recon- nection beyond the cusp and the capturing of magnetosheath plasma during northward IMF. Locally, magnetic noise en- hancement in the Pc1 frequency band occurred simultane- ously with the anomalous radar backscatter, and the absence of such signals at more remote magnetic observatories indi- cates a local generation of the Pc1 turbulence, which is collo- cated with the radar backscatter. Finally, we discuss possible interpretation errors which may be caused by limited obser- vational data.