On the Momentum Transfer From Polar to Equatorial Ionosphere
On the Momentum Transfer From Polar to Equatorial Ionosphere
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DOI：
10.1029/2019ja026760
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
J. Tu;P. Song
中科院分区：
文献类型：
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作者：
J. Tu;P. Song
在空间天气事件期间，来自太阳风的大量能量和动量输入到电离层-热层。一个关键的问题是，如果太阳风-磁层相互作用只驱动极冠中的开放场区域，那么太阳风的能量和动量如何传输到低纬度和赤道电离层。这一重要问题已研究了几十年，但仍然知之甚少，妨碍了空间气象预报能力。在这里，我们使用我们新开发的2.5-D电离层-热层模拟模型，自洽地解决了电子，多离子和中性物质以及电磁场的密度，速度和温度，以研究这个具有挑战性的问题。本研究的重点是电离层对极地磁层对流扰动的快速响应。来自极冠的中性风引起的更长时间尺度的响应将是未来研究的主题。我们表明，动量主要通过快速磁声波从极地电离层转移到赤道电离层，来自源区的扰动传播经历延迟，阻尼和大量反射，电离层/热层表现得像一个低通带滤波器。这项研究的发现为磁层-电离层系统内的耦合过程提供了新的见解。
During space weather events, a large amount of energy and momentum from the solar wind inputs into the ionosphere‐thermosphere. A critical question is that if the solar wind‐magnetosphere interaction drives only the open field region in the polar caps, how the solar wind energy and momentum are transmitted to the low latitude and equatorial ionosphere. This important issue has been studied over decades and is still poorly understood, impeding space weather forecasting ability. Here we use our newly developed 2.5‐D ionosphere‐thermosphere simulation model that self‐consistently solves the density, velocity, and temperature for electrons, multiple ion and neutral species, and electromagnetic fields to study this challenging problem. The focus of the present study is on the prompt response of the ionosphere to a convection disturbance from the polar magnetosphere. The longer time scale responses caused by the neutral winds from the polar caps will be the topic of future studies. We show that the momentum is transferred from polar to equatorial ionosphere predominately by fast magnetosonic waves, and propagation of perturbations from the source region experiences delay, damping, and substantial reflection, and the ionosphere/thermosphere behaves like a low‐band‐pass filter. The finding from this study sheds new insight onto coupling processes within the magnetosphere‐ionosphere system.