Atmospheric confinement of jet streams on Uranus and Neptune
Atmospheric confinement of jet streams on Uranus and Neptune
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DOI：
10.1038/nature12131
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发表时间：
2013-05
期刊：
影响因子：
64.8
通讯作者：
Y. Kaspi;A. Showman;W. Hubbard;O. Aharonson;R. Helled
中科院分区：
文献类型：
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作者：
Y. Kaspi;A. Showman;W. Hubbard;O. Aharonson;R. Helled
观测到的太阳系外行星的云层大气环流以强烈的东西向急流为主。这些风的深度是一个关键的未知因素，它限制了它们的整体动力学、能量学和内部结构。有两种方法可以解释这些强风的存在。第一种观点认为，喷流是由地表附近的浅层大气过程驱动的，而第二种观点认为，大气动力学深入到行星内部。在这里，我们报告，在天王星和海王星的大气动力学的深度可以揭示行星各自的重力场。我们表明，测量到的四阶引力谐波J4将动力学限制在天王星总质量的最外层0.15%和海王星总质量的最外层0.2%。这为动力大气的深度提供了一个比以前提出的更强的限制，并表明动力只限于两颗行星上不超过1000公里深的薄天气层。
The observed cloud-level atmospheric circulation on the outer planets of the Solar System is dominated by strong east–west jet streams. The depth of these winds is a crucial unknown in constraining their overall dynamics, energetics and internal structures. There are two approaches to explaining the existence of these strong winds. The first suggests that the jets are driven by shallow atmospheric processes near the surface,,, whereas the second suggests that the atmospheric dynamics extend deeply into the planetary interiors,. Here we report that on Uranus and Neptune the depth of the atmospheric dynamics can be revealed by the planets’ respective gravity fields. We show that the measured fourth-order gravity harmonic,J4, constrains the dynamics to the outermost 0.15 per cent of the total mass of Uranus and the outermost 0.2 per cent of the total mass of Neptune. This provides a stronger limit to the depth of the dynamical atmosphere than previously suggested, and shows that the dynamics are confined to a thin weather layer no more than about 1,000 kilometres deep on both planets.