HDO and SO 2 thermal mapping on Venus: V. Evidence for a long-term anti-correlation
HDO and SO 2 thermal mapping on Venus: V. Evidence for a long-term anti-correlation
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金星上的 HDO 和 SO 2 热图：V. 长期反相关的证据
DOI：
10.1051/0004-6361/202037741
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发表时间：
2020
影响因子：
6.5
通讯作者：
Atreya, S. K.
中科院分区：
文献类型：
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作者：
Encrenaz, T.;Greathouse, T. K.;Marcq, E.;Sagawa, H.;Widemann, T.;Bézard, B.;Fouchet, T.;Lefèvre, F.;Lebonnois, S.;Atreya, S. K.
自2012年1月以来，我们一直在监测金星上的二氧化硫和水的行为，使用美国宇航局红望远镜设施（IRTF，莫纳克亚天文台）的德克萨斯Echelon Cross-Echelle光谱成像光谱仪。在这里，我们提供了2019年2月和4月在1345 cm−1（7.4 μm）光谱范围内记录的新数据，其中观察到SO2，CO2和HDO（用作H2O的替代品）跃迁。金星的云顶是在大约64公里的高度探测的。在我们以前的研究中，SO2的体积混合比（vmr）估计使用的SO2/CO2线深度比的弱转换; H2O体积混合比来自HDO/CO2线深度比，假设D/H比为200倍的维也纳标准平均海水。正如我们之前的分析所报告的，SO2混合比随着时间的推移和整个磁盘显示出强烈的变化，显示出形成SO2羽流的证据，寿命为几个小时;相反，H2O丰度在磁盘上是非常均匀的，并显示出适度的变化作为时间的函数。我们使用了2019年的数据以及之前的数据集来研究SO2和H2O的长期变化。数据显示了长期的反相关性，相关系数为-0.80;如果分析仅限于2014-2019年的时间段，则该系数为-0.90。作为当地时间的函数的SO2羽流的统计分析证实了我们以前的结果，在10：00左右有一个最小值，在终点附近有两个最大值。相对于当地时间的SO2 vmr的依赖性显示了较高的丰度在晚上的终结者相对于上午。SO2 vmr与经度的相关性在东南极120-200°处表现出一个广泛的最大值，靠近阿佛洛狄忒地地区。然而，这一趋势尚未通过其他测量观察到，尚待证实。
Since January 2012, we have been monitoring the behavior of sulfur dioxide and water on Venus, using the Texas Echelon Cross-Echelle Spectrograph imaging spectrometer at the NASA InfraRed Telescope Facility (IRTF, Mauna Kea Observatory). Here, we present new data recorded in February and April 2019 in the 1345 cm−1 (7.4 μm) spectral range, where SO2, CO2, and HDO (used as a proxy for H2O) transitions were observed. The cloud top of Venus was probed at an altitude of about 64 km. As in our previous studies, the volume mixing ratio (vmr) of SO2 was estimated using the SO2/CO2 line depth ratio of weak transitions; the H2O volume mixing ratio was derived from the HDO/CO2 line depth ratio, assuming a D/H ratio of 200 times the Vienna standard mean ocean water. As reported in our previous analyses, the SO2 mixing ratio shows strong variations with time and also over the disk, showing evidence for the formation of SO2 plumes with a lifetime of a few hours; in contrast, the H2O abundance is remarkably uniform over the disk and shows moderate variations as a function of time. We have used the 2019 data in addition to our previous dataset to study the long-term variations of SO2 and H2O. The data reveal a long-term anti-correlation with a correlation coefficient of −0.80; this coefficient becomes −0.90 if the analysis is restricted to the 2014–2019 time period. The statistical analysis of the SO2 plumes as a function of local time confirms our previous result with a minimum around 10:00 and two maxima near the terminators. The dependence of the SO2 vmr with respect to local time shows a higher abundance at the evening terminator with respect to the morning. The dependence of the SO2 vmr with respect to longitude exhibits a broad maximum at 120–200° east longitudes, near the region of Aphrodite Terra. However, this trend has not been observed by other measurements and has yet to be confirmed.