Tides on Other Earths: Implications for Exoplanet and Palaeo-Tidal Simulations
Tides on Other Earths: Implications for Exoplanet and Palaeo-Tidal Simulations
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DOI：
10.1029/2019gl085746
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发表时间：
2020-06-28
影响因子：
5.2
通讯作者：
Way, M. J.
中科院分区：
文献类型：
--
作者：
Blackledge, B. W.;Green, J. A. M.;Way, M. J.
行星自转演化以及宜居性的关键控制因素是潮汐耗散，在地球上，潮汐耗散主要由海洋潮汐主导。由于系外行星或地球深处的地形未知，因此使用统计系综来限制类地行星上可能的潮汐耗散率。专用潮汐模型与 120 个随机大陆配置一起使用来模拟地球的半日月球潮汐。结果显示，海洋潮汐耗散范围可能跨越 3 个数量级，即 2.3 GW 至 1.9 TW（1 TW=10(12) W）。当考虑模型分辨率时，这与当今地球深海能量学的理论极限相吻合。因此，大陆对潮汐耗散率具有根本性的控制作用，我们认为行星上的板块构造将引起类似于地球的随时间变化的耗散。这将改变数百万年的自转周期，并使潮汐对行星演化的作用进一步复杂化。 简单语言摘要 行星的日长对于宜居性至关重要，因为它调节着太阳辐射在表面接收和重新分配的速率。行星日长的主要控制者是海洋潮汐，因为潮汐能的耗散起到了行星自转的制动作用，从而增加了日长。潮汐对行星上的大陆排列很敏感，但没有任何系外行星表面的细节，而且关于地球在遥远的过去的样子的信息也很有限。地球日长的变化迫使月球后退到更高的轨道，但目前的后退率非常高，不符合我们的月球年龄模型，这意味着潮汐在遥远的过去一定要弱得多。在这里，我们对地球的随机大陆构造进行了一系列潮汐预测，以提供一系列潮汐消散率，从而估计出随着地球大陆变得越来越复杂，远古时期潮汐可能如何演变。这项研究还提供了一系列耗散率，可用于模拟系外行星的旋转和轨道演化。
A key controller of a planet's rotational evolution, and hence habitability, is tidal dissipation, which on Earth is dominated by the ocean tides. Because exoplanet or deep-time Earth topographies are unknown, a statistical ensemble is used to constrain possible tidal dissipation rates on an Earth-like planet. A dedicated tidal model is used together with 120 random continental configurations to simulate Earth's semidiurnal lunar tide. The results show a possible ocean tidal dissipation range spanning 3 orders of magnitude, between 2.3 GW to 1.9 TW (1 TW=10(12) W). When model resolution is considered, this compares well with theoretical limits derived for the energetics of Earth's present-day deep ocean. Consequently, continents exert a fundamental control on tidal dissipation rates and we suggest that plate tectonics on a planet will induce a time-varying dissipation analogous to Earth's. This will alter rotational periods over millions of years and further complicate the role of tides for planetary evolution.Plain Language Summary The daylength of a planet is key for habitability because it regulates the rate with which solar radiation is received and redistributed at the surface. A main controller of a planet's daylength is the ocean tide, because the dissipation of tidal energy works as a brake on the planet's spin, increasing the daylength. Tides are sensitive to the continental arrangement on a planet, but there are no details of the surface of any exoplanet and only limited information of what Earth looked like in the distant past. The change in Earth's daylength forces the Moon to recede into a higher orbit, but the present-day recession rate is very high and does not fit our age models of the moon, implying that the tides must have been much weaker in the distant past. Here, we use a series of tidal predictions for random continental configurations of Earth to provide a range of tidal dissipation rates and thus an estimate of how the tides in the deep past may have evolved as Earth's continents grew more and more complex. This research also provides a range of dissipation rates that can be used for simulations of the rotational and orbital evolution of exoplanets.