A new constraint on HCl abundance at the cloud top of Venus
A new constraint on HCl abundance at the cloud top of Venus
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金星云顶 HCl 丰度的新限制
DOI：
10.1016/j.icarus.2022.115307
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发表时间：
2023
期刊：
影响因子：
3.2
通讯作者：
Sagawa Hideo
中科院分区：
文献类型：
--
作者：
Sato Takao M.;Sagawa Hideo
我们提供了一个新的约束HCl丰度在金星云顶的红外光谱使用交叉分散的高分辨率中阶梯光栅摄谱仪，iSHELL，安装在美国宇航局红外望远镜设施（IRTF）。这项研究调查了以前的地面观测和金星快车掩星测量之间的HCl丰度的不一致性。在2018年8月6日至7日和2020年8月18日至20日（UT）进行了太阳相位角为1.90 °的金星白昼观测，当时金星的下午和早晨分别可见。高光谱分辨能力达80，000和大多普勒频移（每秒13公里），使得测量金星谱线时受到地面谱线的污染较少。我们分析了1-0带中分别位于2775.8和2750.1 cm−1的H35 Cl P（5）和H37 Cl P（6）谱线，以及20001-00001带中与HCl谱线处于相同光谱级的16 O 12 C18 O P-和R-分支谱线。16 O 12 C18 O线被用来推导云顶高度，因为上层云显着影响HCl丰度的反演。云顶具有赤道对称结构。在向赤道±30°的区域内，平均海拔为70.8 ± 0.6km，向高纬度逐渐降低。测得探测高度为70.6 ± 1.1 km时的HCl体积混合比为0.379 ± 0.013 ppm，在±70°范围内没有表现出明显的纬度依赖性。2018年和2020年之间的0.02 ppm差异主要是由时间变化造成的。H35 Cl/H37 Cl丰度比为3.01 ± 0.16，没有明显的纬度依赖性。得到的HCl体积混合比同意与以前的地面测量的结果，这是大约一个数量级大于来自金星快车掩星测量。我们的检索分析中的系统不确定性不能解释这种显著的不一致性。气溶胶散射产生的漫射光对日掩星反演方法的影响有待进一步研究。
We provided a new constraint on HCl abundance at the cloud top of Venus by infrared spectroscopy using a cross-dispersed high-resolution echelle spectrograph, iSHELL, mounted on the NASA Infrared Telescope Facility (IRTF). This study investigated the inconsistency in HCl abundance between previous ground-based observations and Venus Express solar occultation measurements. Venusian dayside observations at a solar phase angle of ∼90° were conducted during August 6–7, 2018, and August 18–20, 2020 (UT), when the Venusian afternoon and morning sides were visible, respectively. The high spectral resolving power of ∼80,000 and large Doppler shift (∼13 km/s) enabled the measurement of Venusian lines with less contamination by terrestrial lines. We analyzed the H35Cl P(5) and H37Cl P(6) lines at 2775.8 and 2750.1 cm−1, respectively, in the 1–0 band, together with16O12C18O P- and R-branch lines of the 20001–00001 band, which fell in the same spectral orders as the HCl lines. The16O12C18O lines were used to derive the cloud top altitude because the upper clouds significantly impacted the retrieval of HCl abundance. The cloud tops had an equatorially symmetric structure. The average altitude was 70.8 ± 0.6 km in the region equatorward of ±30° and decreased toward higher latitudes. The HCl volume mixing ratio was derived as 0.379 ± 0.013 ppm at a probing altitude of 70.6 ± 1.1 km and showed no significant latitudinal dependence within the range of ±70°. A difference of ∼0.02 ppm between 2018 and 2020 would result mainly from temporal variation. The H35Cl/H37Cl abundance ratio was 3.01 ± 0.16, with no prominent latitudinal dependence. The obtained HCl volume mixing ratio agreed with the results of previous ground-based measurements, which were approximately one order of magnitude larger than those derived from Venus Express solar occultation measurements. The systematic uncertainties in our retrieval analysis cannot explain this significant inconsistency. The impact of diffuse light produced from aerosol scattering on the retrieval method for solar occultation measurements should be investigated further to solve this issue.
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DOI：
10.1117/12.2232064
发表时间：
2016
期刊：
Journal of Zhejiang University. Science. B
影响因子：
--
作者：
J. Rayner;A. Tokunaga;D. Jaffe;Morgan B. Bonnet;G. Ching;M. Connelley;Dan Kokubun;C. Lockhart;Eric A. Warmbier
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10.1016/j.jqsrt.2013.07.002
发表时间：
2013-11-01
影响因子：
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DOI：
--
发表时间：
2015
期刊：
影响因子：
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DOI：
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发表时间：
2012
期刊：
影响因子：
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作者：
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