Oxford Research Encyclopedia of Planetary Science
Oxford Research Encyclopedia of Planetary Science
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牛津研究行星科学百科全书
DOI：
10.1093/acrefore/9780190647926.013.227
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Achilleos N
中科院分区：
文献类型：
--
作者：
Achilleos N
磁层-电离层耦合过程涉及磁化行星与其空间环境或磁层之间的大量能量和动量的传输。这种传输包括沿着磁力线流动的延伸的、全球的电流片。一些带电粒子将当前的雨水带到地球的上层大气中，激发极光--靠近磁极的美丽光线显示，这是耦合过程物理学的重要标志。地球、木星和土星都有磁层，但它们极光发射的详细物理来源在不同的行星上是不同的。地球的极光主要是由其磁层与上游太阳风的相互作用驱动的--上游太阳风是持续从太阳发出的等离子体流。这种相互作用对磁层内的等离子体施加了一种特殊的流动模式，这反过来又决定了电流和极光的形态和强度。另一方面，木星是一个巨大的快速旋转体，其主要极光椭圆形被认为是来自上层大气和磁层中旋转的盘状等离子体之间的角动量传输。土星的极光行为与太阳风相关的机制一致，但土星极光发射也有规律的变化，这与在磁层等离子体和高层大气/电离层的局部涡流之间传输能量的旋转电流系统是一致的。
The process of magnetosphere-ionosphere coupling involves the transport of vast quantities of energy and momentum between a magnetized planet and its space environment, or magnetosphere. This transport involves extended, global sheets of electrical current, which flows along magnetic field lines. Some of the charged particles, which carry this current rain down onto the planet’s upper atmosphere and excite aurorae–beautiful displays of light close to the magnetic poles, which are an important signature of the physics of the coupling process. The Earth, Jupiter, and Saturn all have magnetospheres, but the detailed physical origin of their auroral emissions differs from planet to planet. The Earth’s aurora is principally driven by the interaction of its magnetosphere with the upstream solar wind—a flow of plasma continually emanating from the Sun. This interaction imposes a particular pattern of flow on the plasma within the magnetosphere, which in turn determines the morphology and intensity of the currents and aurorae. Jupiter, on the other hand, is a giant rapid rotator, whose main auroral oval is thought to arise from the transport of angular momentum between the upper atmosphere and the rotating, disc-like plasma in the magnetosphere. Saturn exhibits auroral behavior consistent with a solar wind–related mechanism, but there is also regular variability in Saturn’s auroral emissions, which is consistent with rotating current systems that transport energy between the magnetospheric plasma and localized vortices of flow in the upper atmosphere/ionosphere.