Multi‐instrument, high‐resolution imaging of polar cap patch transportation
Multi‐instrument, high‐resolution imaging of polar cap patch transportation
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DOI：
10.1002/2015rs005672
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发表时间：
2013-12
期刊：
影响因子：
1.6
通讯作者：
E. Thomas;K. Hosokawa;J. Sakai;J. Baker;J. Ruohoniemi;S. Taguchi;K. Shiokawa;Y. Otsuka;A. Coster;J. St.‐Maurice;K. McWilliams
中科院分区：
文献类型：
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作者：
E. Thomas;K. Hosokawa;J. Sakai;J. Baker;J. Ruohoniemi;S. Taguchi;K. Shiokawa;Y. Otsuka;A. Coster;J. St.‐Maurice;K. McWilliams
当遇到与离散等离子体结构或贴片相关的急剧电子密度梯度时，高纬度极帽中的跨层无线电信号很容易退化。在2012年1月22日的一次地磁风暴间隔期间，对极地帽片的多仪器测量进行了检查。我们首次使用GPS总电子含量(TEC)、全天气辉成像仪(ASIS)和超级双极光雷达网(SuperDARN)高频雷达后向散射的组合来监测跨越极冠的高空间和时间分辨率斑块的传输1-2小时。这些数据集的同步测量允许连续跟踪斑块位置、水平范围和速度，尽管主要技术的观测条件不利(例如，ASI数据中的日照区域)。相对粗糙的全球GPS TEC测量中的斑块状特征与高分辨率ASI数据绘制的斑块状特征之间的空间配置非常好，这表明GPS TEC可以在斑块穿过极冠时用于连续跟踪。与以前观测到的在弱扰动条件下形成的雪茄状斑块不同，本区间(500-800公里)中斑块的黎明-黄昏范围相对较窄，这表明与纵向受限的等离子体源区有关，例如风暴增强密度(SED)羽流。SuperDARN观测表明，背向散射功率的增强对应于光学斑块，并首次证明了光学斑块的运动与背景等离子体对流速度是一致的。
Transionospheric radio signals in the high‐latitude polar cap are susceptible to degradation when encountering sharp electron density gradients associated with discrete plasma structures, or patches. Multi‐instrument measurements of polar cap patches are examined during a geomagnetic storm interval on 22 January 2012. For the first time, we monitor the transportation of patches with high spatial and temporal resolution across the polar cap for 1–2 h using a combination of GPS total electron content (TEC), all‐sky airglow imagers (ASIs), and Super Dual Auroral Radar Network (SuperDARN) HF radar backscatter. Simultaneous measurements from these data sets allow for continuous tracking of patch location, horizontal extent, and velocity despite adverse observational conditions for the primary technique (e.g., sunlit regions in the ASI data). Spatial collocation between patch‐like features in relatively coarse but global GPS TEC measurements and those mapped by high‐resolution ASI data was very good, indicating that GPS TEC can be applied to track patches continuously as they are transported across the polar cap. In contrast to previous observations of cigar‐shaped patches formed under weakly disturbed conditions, the relatively narrow dawn‐dusk extent of patches in the present interval (500–800 km) suggests association with a longitudinally confined plasma source region, such as storm‐enhanced density (SED) plume. SuperDARN observations show that the backscatter power enhancements corresponded to the optical patches, and for the first time we demonstrate that the motion of the optical patches was consistent with background plasma convection velocities.