Large stationary gravity wave in the atmosphere of Venus
Large stationary gravity wave in the atmosphere of Venus
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DOI：
10.1038/ngeo2873
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发表时间：
2017-02-01
影响因子：
18.3
通讯作者：
Yamazaki, Atsushi
中科院分区：
文献类型：
--
作者：
Fukuhara, Tetsuya;Futaguchi, Masahiko;Yamazaki, Atsushi
金星被厚厚的硫酸云所覆盖，这些硫酸云向西移动，因为整个上层大气的旋转速度比行星本身快得多。在大约65公里高度的云顶，小尺度特征主要由速度约为100毫秒（-1）的背景风携带。相比之下，行星尺度的大气特征被观察到比背景风移动得稍快或稍慢，这一现象被解释为反映了行星尺度波的传播。在这里，我们报告了一个半球间的弓形结构的检测延伸10,000公里，在云顶水平的金星在中红外和紫外图像从日本轨道器Akatsuki。经过几天的观测，弓形结构在缓慢旋转的表面上的高地上方保持相对固定的位置，尽管背景大气超旋转。我们认为，弓形结构的结果是在低层大气中产生的大气重力波的山脉地形，然后向上传播。数值模拟为这种解释提供了初步的支持，但山脉重力波的形成和传播仍然难以与金星上假设的近地表条件相协调。我们认为，在大气深处的风可能是空间或时间比以前认为的更易变。
The planet Venus is covered by thick clouds of sulfuric acid that move westwards because the entire upper atmosphere rotates much faster than the planet itself. At the cloud tops, about 65 km in altitude, small-scale features are predominantly carried by the background wind at speeds of approximately 100 ms(-1). In contrast, planetary-scale atmospheric features have been observed to move slightly faster or slower than the background wind, a phenomenon that has been interpreted to reflect the propagation of planetary-scale waves. Here we report the detection of an interhemispheric bow-shaped structure stretching 10,000 km across at the cloud-top level of Venus in middle infrared and ultraviolet images from the Japanese orbiter Akatsuki. Over several days of observation, the bow-shaped structure remained relatively fixed in position above the highland on the slowly rotating surface, despite the background atmospheric super rotation. We suggest that the bow-shaped structure is the result of an atmospheric gravity wave generated in the lower atmosphere by mountain topography that then propagated upwards. Numerical simulations provide preliminary support for this interpretation, but the formation and propagation of a mountain gravity wave remain difficult to reconcile with assumed near-surface conditions on Venus. We suggest that winds in the deep atmosphere may be spatially or temporally more variable than previously thought.