标题： 木星微量碳氢化合物的丰度：从“旅行者”号到“卡西尼”号 显示英文标题

标题： Abundances of Jupiter's Trace Hydrocarbons From Voyager and Cassini

摘要： 旅行者号航天器于1979年飞掠木星，二十多年后卡西尼号于2000年再次飞掠木星，为我们提供了来自两个不同历史时期的独特数据集，使我们能够研究大气中的季节变化。 本文中，我们对旅行者1号IRIS和卡西尼CIRS这两台仪器的热红外光谱的纬向平均值进行建模，以获取温度的垂直和经向分布，以及两种微量碳氢化合物——乙炔（C₂H₂）和乙烷（C₂H₆）的丰度。 这些气体的空间分布受化学过程和动力学过程的共同控制，因此它们的观测分布使我们能够深入了解这两种过程。 我们发现，这两种气体所描绘出的季节变化图景截然不同。 虽然在2000年（北半球夏至）时C₂H₆丰度的二维剖面图相较于1979年（北半球秋分）略有增加且更对称，但从赤道到极地的增加这一主要趋势仍然存在。 对于C₂H₂而言，旅行者号时代几乎不存在纬向变化，而卡西尼号时代则显示出南北半球向极地方向的显著减少。 目前，这些实验结果领先于解释，因为在比较中没有可用的关于二维木星季节性化学变化的已发表模型。 显示英文摘要

摘要： The flybys of Jupiter by the Voyager spacecraft in 1979, and over two decades later by Cassini in 2000, have provided us with unique datasets from two different epochs, allowing the investigation of seasonal change in the atmosphere. In this paper we model zonal averages of thermal infrared spectra from the two instruments, Voyager 1 IRIS and Cassini CIRS, to retrieve the vertical and meridional profiles of temperature, and the abundances of the two minor hydrocarbons, acetylene (C2H2) and ethane (C2H6). The spatial variation of these gases is controlled by both chemistry and dynamics, and therefore their observed distribution gives us an insight into both processes. We find that the two gases paint quite different pictures of seasonal change. Whilst the 2-D cross-section of C2H6 abundance is slightly increased and more symmetric in 2000 (northern summer solstice) compared to 1979 (northern fall equinox), the major trend of equator to pole increase remains. For C2H2 on the other hand, the Voyager epoch exhibits almost no latitudinal variation, whilst the Cassini era shows a marked decrease polewards in both hemispheres. At the present time, these experimental findings are in advance of interpretation, as there are no published models of 2-D Jovian seasonal chemical variation available for comparison.