Keiling A, Wygant J R, Cattell C A, Mozer F S, Russell C T
Department of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55144, USA.
Science. 2003 Jan 17;299(5605):383-6. doi: 10.1126/science.1080073.
Large-scale, electric currents flowing 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 (Alfvén 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 Alfvén waves.
沿磁力线流入地球极地地区的大规模电流被认为是为电离层极光提供能量的主要来源。然而，我们发现了来自电磁波（阿尔文波）的全球贡献的证据。从“极地”号航天器在1年的时间里收集的数据表明，在25000至38000公里高度处的波动电磁能量流描绘出了统计极光卵。沿极光卵分布的单个事件的坡印廷通量大于每平方厘米每秒5尔格，这足以驱动极光加速过程。这一证据表明，除了磁场对齐电流外，日侧和夜侧极光在全球范围内还由这些高空阿尔文波的能量流提供动力。
