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首页> 外文期刊>Icarus: International Journal of Solar System Studies >Cloud top structure of Venus revealed by Subaru/COMICS mid-infrared images
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Cloud top structure of Venus revealed by Subaru/COMICS mid-infrared images

机译:斯巴鲁/ COMICS中红外图像揭示金星的云顶结构

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摘要

We have investigated the cloud top structure of Venus by analyzing ground-based images taken at the mid-infrared wavelengths of 8.66 mu m and 11.34 mu m. Venus at a solar phase angle of similar to 90 degrees, with the morning terminator in view, was observed by the Cooled Mid-Infrared Camera and Spectrometer (COMICS), mounted on the 8.2-m Subaru Telescope, during the period October 25-29, 2007. The disk-averaged brightness temperatures for the observation period are similar to 230 K and similar to 238 K at 8.66 mu m and 11.34 Inn, respectively. The obtained images with good signal-to-noise ratio and with high spatial resolution (similar to 200 km at the sub-observer point) provide several important findings. First, we present observational evidence, for the first time, of the possibility that the westward rotation of the polar features (the hot polar spots and the surrounding cold collars) is synchronized between the northern and southern hemispheres. Second, after high-pass filtering, the images reveal that streaks and mottled and patchy patterns are distributed over the entire disk, with typical amplitudes of similar to 0.5 K, and vary from day to day. The detected features, some of which are similar to those seen in past UV images, result from inhomogeneities of both the temperature and the cloud top altitude. Third, the equatorial center-to-limb variations of brightness temperatures have a systematic day-night asymmetry, except those on October 25, that the dayside brightness temperatures are higher than the nightside brightness temperatures by 0-4 K under the same viewing geometry. Such asymmetry would be caused by the propagation of the migrating semidiurnal tide. Finally, by applying the lapse rates deduced from previous studies, we demonstrate that the equatorial center-to-limb curves in the two spectral channels give access to two parameters: the cloud scale height Hand the cloud top altitude z(c), The acceptable models for data on October 25 are obtained at H=2.4-4.3 km and z(c)= 66-69 km; this supports previous results determined from spacecraft observations. (C) 2014 Elsevier Inc. All rights reserved.
机译:我们通过分析在8.66微米和11.34微米的中红外波长拍摄的地面图像,研究了金星的云顶结构。在10月25日至29日期间,安装在8.2米斯巴鲁望远镜上的冷却中红外相机和光谱仪(COMICS)观测到太阳相角接近90度的金星,并伴有晨起的终结者。 ,观测时段的磁盘平均亮度温度分别在8.66微米和11.34 Inn时分别接近230 K和238K。所获得的图像具有良好的信噪比和高空间分辨率(在次观察点处接近200 km)提供了一些重要发现。首先,我们首次提出观测证据,证明南北半球之间极地特征(热极点和周围的冷领)向西旋转的可能性。其次,经过高通滤波后,图像显示出条纹,斑驳和斑驳的图案分布在整个磁盘上,典型振幅类似于0.5 K,并且每天都在变化。检测到的特征(其中一些与过去的UV图像相似)是由于温度和云顶高度的不均匀性造成的。第三,除了10月25日的赤道温度变化外,赤道中心到边缘的昼夜系统性不对称,在相同的观察几何条件下,白天的亮度温度比夜间的亮度温度高0-4K。这种不对称性将由迁移的半日潮的传播引起。最后,通过应用先前研究得出的衰减率,我们证明了两个光谱通道中的赤道中心至边缘曲线可访问两个参数:云规模高度手云最高高度z(c),可接受在H = 2.4-4.3 km和z(c)= 66-69 km处获得了10月25日的数据模型;这支持了从航天器观测确定的先前结果。 (C)2014 Elsevier Inc.保留所有权利。

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