The spacecraft Voyager 2 UVS occultation experiments measured the ultraviolet absorption properties of the upper atmosphere of Saturn. In the extreme-ultraviolet wavelength region from 1300 Å to 1700 Å, CH₄, C₂H₂, C₂H₄, C₂H₆ and C₄H₂ are the major absorbers in the Saturnian upper atmosphere. In this dissertation, using the linear constrained matrix method, the Saturnian stellar EUV occultation data has been inverted. This results in, for the first time, the number density distributions of the 5 major hydrocarbons over an altitude range from 1030 km to 630 km. The synthetic transmission curves based on these inverted distributions exhibit excellent agreement with the observed transmission curves in all usable wavelength channels. There are two major findings in the Saturnian upper atmosphere from the inverted hydrocarbon profiles: (1) The number densities of CH₄ and C₂H₆ are comparable. It is even likely that there is more C₂H₆ than CH₄ in Saturn's upper atmosphere between 1000 km and 800 km. (2) C₂H₄, rather than C₂H₂, is the 3rd most abundant hydrocarbon. From 1000 km down to 600 km, the number density of C₂H₄ is greater than the number density of C₂H₂. These two findings are generally in conflict with the expectations from photochemical models for the atmospheres of the giant planets.
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机译:太空旅行者2号旅行者的紫外线掩星实验测量了土星高层大气的紫外线吸收特性。在1300埃至1700埃的极紫外波长范围内,CH 3,C 2 H 2,C 2 H 4,C 2 H 4和C 4 H 2是土星上层大气的主要吸收体。本文采用线性约束矩阵方法,对土星恒星EUV掩星数据进行了反演。这首次导致在1030 km至630 km高度范围内5种主要烃的数量密度分布。基于这些反向分布的合成透射曲线与在所有可用波长通道中观察到的透射曲线表现出极好的一致性。从反演的碳氢化合物分布图可以看出,在土星上层大气中有两个主要发现:(1)CH 3和C 2 H 3的数密度是可比的。在土星的1000至800公里的高空大气中,甚至有可能比CH 3的C 2 H 3含量更高。 (2)C 2 H 3而不是C 2 H 2是第三大最丰富的烃。从1000公里到600公里,C 2 H 4的数密度大于C 2 H 2的数密度。这两个发现通常与光化学模型对巨型行星大气的期望相抵触。
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