An asymmetric distribution of lakes on Titan as a possible consequence of orbital forcing
An asymmetric distribution of lakes on Titan as a possible consequence of orbital forcing
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DOI：
10.1038/ngeo698
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发表时间：
2009-12-01
影响因子：
18.3
通讯作者：
Elachi, C.
中科院分区：
文献类型：
--
作者：
Aharonson, O.;Hayes, A. G.;Elachi, C.
在土星卫星土卫六的高纬度地区发现了一组充满或部分充满液态碳氢化合物的湖泊和空湖盆地。这些特征是由卡西尼号轨道飞行器上的雷达仪器绘制的。在这里，我们量化了湖泊和盆地的分布，并在它们的发生中显示出明显的半球不对称。然而，北部高纬度地区的大部分地区都被填满的和空的湖泊所覆盖(5)，南半球的相同纬度地区基本上没有这样的特征。我们提出，除了已知的季节变化外，观测到的湖泊分布差异可能是由土卫六上季节的不对称性引起的，这是由土星绕太阳轨道的偏心造成的。我们认为，蒸发和降水之间平衡的半球差异可能导致土卫六的一个半球积聚湖泊。这种效应将被轨道的动态变化所调节，并与之相反。我们提出，就像地球的冰期循环一样，由此产生的剧烈的水文循环(6)具有数万年的周期，并导致极地纬度地区活跃的地表地质变化。
A set of lakes filled or partially filled with liquid hydrocarbon and empty lake basins have been discovered in the high latitudes of Saturn's moon Titan(1). These features were mapped by the radar instrument on the Cassini orbiter(1-4). Here we quantify the distribution of the lakes and basins, and show a pronounced hemispheric asymmetry in their occurrence. Whereas significant fractions of the northern high latitudes are covered by filled and empty lakes(5), the same latitudes in the southern hemisphere are largely devoid of such features. We propose that in addition to known seasonal changes, the observed difference in lake distribution may be caused by an asymmetry in the seasons on Titan that results from the eccentricity of Saturn's orbit around the Sun. We suggest that the consequent hemispheric difference in the balance between evaporation and precipitation could lead to an accumulation of lakes in one of Titan's hemispheres. This effect would be modulated by, and reverse with, dynamical variations in the orbit. We propose that much like in the Earth's glacial cycles, the resulting vigorous hydrologic cycle(6) has a period of tens of thousands of years and leads to active geologic surface modification in the polar latitudes.