Generation of auroral omega bands by shear instability of the neutral winds
Generation of auroral omega bands by shear instability of the neutral winds
复制标题
中性风的剪切不稳定性产生极光欧米茄带
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
R. Walterscheid
中科院分区：
文献类型：
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作者：
L. Lyons;R. Walterscheid
与极光有关的电子沉降大大增加了电离层导电E区中通过离子拖曳的热层中性风加速。这种增加的加速度可以导致显著的水平风切变的发展，我们发现这是不稳定的Kelvin-Helmholtz剪切不稳定性。数值模拟对强烈的午夜后扩散极光的中性反应显示，极光中形成了E区“急流”，一小时后风速峰值超过700米/秒。我们认为，这种喷流产生不稳定的开尔文-亥姆霍兹波，它可以驱动波离散极光沿着极边界的预先存在的扩散极光。我们认为，这样的极光波，驱动的中性风，形成向东传播的波（欧米茄带）偶尔观察到沿着极向边界的午夜后扩散极光。我们还发现中性风切变，发展离散极光弧是不稳定的，但是，我们不希望由此产生的风浪驱动显着极光波沿着离散弧。
Thermospheric neutral wind acceleration via ion drag in the conducting E-region of the ionosphere is greatly increased by electron precipitation associated with auroras. This increased acceleration can lead to the development of significant horizontal wind shears, which we find are unstable to the Kelvin-Helmholtz shear instability. Numerical simulation of the neutral response to an intense, postmidnight, diffuse aurora shows the formation of an E-region “jet stream” within the aurora, with peak winds speeds >700 m/s after one hour. We propose that this jet stream produces unstable Kelvin-Helmholtz waves, which can drive waves of discrete aurora along the poleward boundary of the preexisting diffuse aurora. We suggest that such auroral waves, driven by the neutral winds, form eastward propagating waves (omega bands) occasionally observed along the poleward boundary of postmidnight diffuse auroras. We also find neutral wind shears that develop in response to discrete auroral arcs to be unstable; however we do not expect the resulting wind waves to drive significant auroral waves along discrete arcs.