Variations in Titan’s dune orientations as a result of orbital forcing
Variations in Titan’s dune orientations as a result of orbital forcing
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DOI：
10.1016/j.icarus.2015.11.036
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发表时间：
2016-05
期刊：
影响因子：
3.2
通讯作者：
G. McDonald;A. Hayes;R. Ewing;J. Lora;C. Newman;T. Tokano;A. Lucas;A. Soto;Gang Chen
中科院分区：
文献类型：
--
作者：
G. McDonald;A. Hayes;R. Ewing;J. Lora;C. Newman;T. Tokano;A. Lucas;A. Soto;Gang Chen
风吹沙丘是泰坦赤道地区气候历史的记录。通过与土卫六的历史轨道配置（由土星轨道的拱点岁差产生）的气候条件的建模，我们提出的证据表明，沙丘的方向受到轨道强迫。3土卫六大气环流模式（GCMs）结合沉积物输运模式的分析提供了第一个直接相互比较的结果，从不同的土卫六GCMs。我们报告的沙丘方向的变化预测不同的轨道时代高达70°。尽管大气环流模型对轨道强迫的响应各不相同，但在所有模型中，轨道对沙丘方向的影响都很显着。此外，两个模型与表面地形之间几乎一致，5个沙丘场中有3个与最近轨道周期的观测相匹配。通过与卡西尼号的观测结果进行比较，我们发现所观察到的沙丘方向与先前轨道配置或其组合的模型最吻合，代表了周期的较大部分。我们的结论是，轨道强迫可能是一个重要的因素，在管理目前的沙丘方向观察土卫六，并应考虑在模拟沙丘的演变。
Wind-blown dunes are a record of the climatic history in Titan’s equatorial region. Through modeling of the climatic conditions associated with Titan’s historical orbital configurations (arising from apsidal precessions of Saturn’s orbit), we present evidence that the orientations of the dunes are influenced by orbital forcing. Analysis of 3 Titan general circulation models (GCMs) in conjunction with a sediment transport model provides the first direct intercomparison of results from different Titan GCMs. We report variability in the dune orientations predicted for different orbital epochs of up to 70°. Although the response of the GCMs to orbital forcing varies, the orbital influence on the dune orientations is found to be significant across all models. Furthermore, there is near agreement among the two models run with surface topography, with 3 out of the 5 dune fields matching observation for the most recent orbital cycle. Through comparison with observations by Cassini, we find situations in which the observed dune orientations are in best agreement with those modeled for previous orbital configurations or combinations thereof, representing a larger portion of the cycle. We conclude that orbital forcing could be an important factor in governing the present-day dune orientations observed on Titan and should be considered when modeling dune evolution.