Spatial and Temporal Variability of the 365-nm Albedo of Venus Observed by the Camera on Board Venus Express
Spatial and Temporal Variability of the 365-nm Albedo of Venus Observed by the Camera on Board Venus Express
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金星快车上的相机观测到的金星 365 nm 反照率的时空变化
DOI：
10.1029/2019je006271
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
S. Watanabe
中科院分区：
文献类型：
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作者：
Lee;Y. J.;P. Kopparla;J. Peralta;S. E. Schroder;T. Imamura;T. Kouyama;S. Watanabe
我们绘制了2006-2014年金星大气层365 nm波长的分布图，使用的是金星快车上的金星监测相机（VMC）采集的图像。我们选择了所有具有金星全局视图的图像，以研究经度如何依赖于经度。Bertaux等人（2016，https：//doi.org/10.1002/2015JE004958）报告了在西经100°附近的一个山峰，并推测与阿芙罗狄蒂山脉有关。我们发现，这个峰值很可能是一个伪影，是由长期的赤道变化加上经度上数据采样的相当大的时间间隔造成的。我们还使用了一个子集的图像，以调查如何依赖于当地时间，只选择南极观看图像的日面（当地时间7-17小时）。Akatsuki在下午晚些时候在283 nm和10 μm处观察到山引起的波（Fukuhara等人，2017年，https：//doi.org/10.1038/ngeo2873）。我们预计这种波的存在可能会引入365 nm的周期性变化，周期为一个太阳日（116.75个地球日）。我们在当地时间15：30-16：00和低纬度地区寻找了这样一个周期性峰值，但没有找到。总之，我们发现，无论是短期还是长期的时间周期变化，都主导着任何随经度和当地时间的系统变化。VMC昼侧观测的性质限制了沿沿着等高线的常规数据采样，因此，如果存在纵向变化，则难以提取。我们的结论是，在该数据集中，金星表面对365纳米反射率的任何影响都可以忽略不计。
We mapped the distribution of the 365‐nm albedo of the Venus atmosphere over the years 2006–2014, using images acquired by the Venus Monitoring Camera (VMC) on board Venus Express. We selected all images with a global view of Venus to investigate how the albedo depends on longitude. Bertaux et al. (2016, https://doi.org/10.1002/2015JE004958) reported a peak in albedo around 100° longitude and speculated on an association with the Aphrodite Terra mountains. We show that this peak is most likely an artifact, resulting from long‐term albedo variations coupled with considerable temporal gaps in data sampling over longitude. We also used a subset of images to investigate how the albedo depends on local time, selecting only south pole viewing images of the dayside (local times 7–17 hr). Akatsuki observed mountain‐induced waves in the late afternoon at 283 nm and 10 μm (Fukuhara et al., 2017, https://doi.org/10.1038/ngeo2873). We expect that the presence of such waves may introduce 365‐nm albedo variations with a periodicity of one solar day (116.75 Earth days). We searched for such a periodicity peak at 15:30–16:00 local time and low latitudes but did not find it. In conclusion, we find that temporal albedo variations, both short and long term, dominate any systematic variations with longitude and local time. The nature of VMC dayside observations limits regular data sampling along longitudes, so longitudinal variations, if they exist, are difficult to extract. We conclude that any influence by the Venus surface on 365‐nm albedo is negligible within this data set.