Azimuthal flow bursts in the inner plasma sheet and possible connection with SAPS and plasma sheet earthward flow bursts
Azimuthal flow bursts in the inner plasma sheet and possible connection with SAPS and plasma sheet earthward flow bursts
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DOI：
10.1002/2015ja021023
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发表时间：
2015-06
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通讯作者：
L. Lyons;Y. Nishimura;B. Gallardo‐Lacourt;M. Nicolls;S. Chen;D. Hampton;W. Bristow;J. Ruohoniemi;N. Nishitani;E. Donovan;V. Angelopoulos
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作者：
L. Lyons;Y. Nishimura;B. Gallardo‐Lacourt;M. Nicolls;S. Chen;D. Hampton;W. Bristow;J. Ruohoniemi;N. Nishitani;E. Donovan;V. Angelopoulos
我们结合了雷达观测和极光图像扑克平坦的非相干散射雷达离子中性观测在热层活动中，以显示向西移动，本地化的极光增亮附近的极光赤道边界的共同发生，并显示其与方位移动的气流爆发附近或在亚极光偏振流（SAPS）区域内。这些结果表明，SAPS区域，而不是由相对稳定的质子降水和向西流动，可以有快速变化的流量，速度变化从~100米/秒到~1公里/秒，在短短几分钟内。极光增亮与弱电子降水的爆发有关，这些爆发随西向流爆发向西移动并延伸到SAPS区。此外，我们的观察表明，方位移动流爆发往往连接到地球（赤道方向的电离层）等离子体片流爆发的证据。这表明，而不是停止或反弹，一些流动爆发后，到达内等离子体片的方位角转向，并导致强方位角流的爆发。大尺度对流模式对气流爆发的一般引导也有证据，黄昏对流内的气流爆发在方位角上转向西方，而黎明单体内的气流爆发转向东方。这里考虑的SAPS区域流动结构的可能性，可能会连接到本地化的流量增强从极冠，跨夜侧极光极向边界，并导致流量爆发等离子体片内值得进一步考虑。
We have combined radar observations and auroral images obtained during the Poker Flat Incoherent Scatter Radar Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the subauroral polarization stream (SAPS) region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds varying from ~100 m/s to ~1 km/s in just a few minutes. The auroral brightenings are associated with bursts of weak electron precipitation that move westward with the westward flow bursts and extend into the SAPS region. Additionally, our observations show evidence that the azimuthally moving flow bursts often connect to earthward (equatorward in the ionosphere) plasma sheet flow bursts. This indicates that rather than stopping or bouncing, some flow bursts turn azimuthally after reaching the inner plasma sheet and lead to the bursts of strong azimuthal flow. Evidence is also seen for a general guiding of the flow bursts by the large‐scale convection pattern, flow bursts within the duskside convection being azimuthally turned to the west, and those within the dawn cell being turned toward the east. The possibility that the SAPS region flow structures considered here may be connected to localized flow enhancements from the polar cap that cross the nightside auroral poleward boundary and lead to flow bursts within the plasma sheet warrants further consideration.