The Ultraviolet Spectrograph (UVS) instrument on the Juno mission records far-ultraviolet reflected sunlight from Jupiter. These spectra are sensitive to the abundances of chemical species in the upper atmosphere and to the distribution of the stratospheric haze layer. We combine observations from the first 30 perijoves of the mission in order to study the meridional distribution of acetylene (C₂H₂) in Jupiter's stratosphere. We find that the abundance of C₂H₂ decreases toward the poles by a factor of 2–4, in agreement with previous analyses of mid-infrared spectra. This result is expected from insolation rates: near the equator, the UV solar flux is higher, allowing more C₂H₂ to be generated from the UV photolysis of CH₄. The decrease in abundance toward the poles suggests that horizontal mixing rates are not rapid enough to homogenize the latitudinal distribution.

中文翻译：

---

来自朱诺号 UVS 观测的木星平流层中 C2H2 的经向变化

朱诺号任务中的紫外线光谱仪 (UVS) 仪器记录了来自木星的远紫外线反射阳光。这些光谱对高层大气中化学物质的丰度和平流层霾层的分布很敏感。为了研究木星平流层中乙炔 (C ₂ H ₂ )的经向分布，我们结合了任务前 30 个 perijoves 的观测结果。我们发现 C ₂ H ₂的丰度朝着两极减少了 2-4 倍，这与之前对中红外光谱的分析一致。这个结果是日照率预期的结果：在赤道附近，紫外线太阳通量更高，允许更多的 C ₂ H ₂由 CH ₄的紫外光解产生。向两极的丰度减少表明水平混合速率不足以使纬度分布均匀化。