The global morphology of wave Poynting flux: Powering the aurora
The global morphology of wave Poynting flux: Powering the aurora
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DOI：
10.1126/science.1080073
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发表时间：
2003-01-17
期刊：
影响因子：
56.9
通讯作者：
Russell, CT
中科院分区：
文献类型：
--
作者：
Keiling, A;Wygant, JR;Russell, CT
沿着磁场线流入地球两极的大规模电流被认为是电离层极光能量的主要来源。然而，我们发现了电磁波（阿尔文波）对全球影响的证据。极地航天器在一年的时间里收集的数据显示，在 25,000 至 38,000 公里高度处的电磁波能量流描绘了统计极光椭圆形。沿极光椭圆形分布的单个事件的坡印廷通量大于每秒每平方厘米 5 尔格，这足以为极光加速过程提供动力。这一证据表明，除了与磁场一致的电流之外，白天和夜晚的极光在全球范围内都是由这些高空阿尔文波的能量流提供动力的。
Large-scale, electric currents owing along magnetic field lines into the polar regions of Earth are thought to be the main contributors of the energy that powers the ionospheric aurora. However, we have found evidence for global contributions from electromagnetic waves (Alfven waves). Data that were collected from the Polar spacecraft over the course of 1 year show that the flow of wave electromagnetic energy at altitudes of 25,000 to 38,000 kilometers delineates the statistical auroral oval. The Poynting flux of individual events distributed along the auroral oval was larger than 5 ergs per square centimeter per second, which is sufficient to power auroral acceleration processes. This evidence suggests that in addition to magnetic field-aligned currents, the dayside and nightside aurora is globally powered by the energy flow of these high-altitude Alfven waves.