由VLT/MUSE、卡西尼号/VIMS、IRTF/SpeX和朱诺号/JIRAM的可见光到近红外观测确定的木星赤道大气中的云和气氨垂直剖面
Cloud and ammonia vertical profiles in the equatorial atmosphere of Jupiter determined from visible to near-IR observations made by VLT/MUSE, Cassini/VIMS, IRTF/SpeX and Juno/JIRAM
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中文总结 AI 辅助
该研究通过多设备观测数据构建木星赤道大气0.1至10巴范围的云/氨组合模型，云模型含三个部分，氨剖面与云剖面紧密相关，还分析了不同波长下云粒子特性及相关现象成因。
中文摘要 AI 辅助
我们提出了一个适用于木星赤道大气0.1至10巴范围的云/氨组合模型，该模型与VLT/MUSE、卡西尼号/VIMS、IRTF/SpeX和朱诺号/JIRAM在0.35至5.15微米一系列观测几何条件下的观测结果一致。我们的云模型有三个组成部分：1）1 - 2巴处的光学厚下层云（半径r约10微米）；2）约0.55巴处的光学薄上层云（r约10微米）；3）位于主要下层云内的一层蓝色吸收发色团颗粒（r约0.2微米）。氨剖面与云剖面紧密相连，下层云与氨丰度的初始下降重合，上层云与氨凝结水平重合。下层大云粒子在可见光波长下高度散射，使阳光能透过云层并从深层大气进行瑞利散射。在5微米处，下层云粒子吸收性更强，带/区差异主要由这些粒子的单次散射反照率变化引起，其次由云不透明度变化引起。下层云粒子的光谱特性可能与水冰成分一致。上层云粒子在3微米附近需要一个独特的吸收带，可能与氨冰成分一致。我们注意到模型中不需要单独的高层光化学霾。相反，我们发现甲烷吸收波长处看到的特征是由上层云层不透明度和垂直范围的变化引起的。
英文摘要
We present a combined cloud/ammonia model for Jupiter's equatorial atmosphere from 0.1 to 10 bar, consistent with observations made at a range of observation geometries from 0.35 to 5.15 $μ$m by VLT/MUSE, Cassini/VIMS, IRTF/SpeX and Juno/JIRAM. Our cloud model has three components: 1) an optically-thick lower cloud (radius $r$$\sim$$10$ $μ$m) at 1-2 bar; 2) an optically-thin upper cloud ($r$$\sim$$10$ $μ$m) at $\sim$0.55 bar; and 3) a layer of blue-absorbing chromophore particles ($r$$\sim$$0.2$ $μ$m) situated within the main lower cloud. The ammonia profile is intimately linked with the cloud profile with the lower cloud coinciding with an initial drop in ammonia abundance and the upper cloud coinciding with the ammonia condensation level. The large lower cloud particles are highly scattering at visible wavelengths, allowing sunlight to scatter through the clouds and be Rayleigh-scattered from the deep atmosphere. At 5 $μ$m, the lower cloud particles are found to be more absorbing, with the belt/zone differences mostly accounted for by changes in the single-scattering albedo of these particles and secondarily by changes in the cloud opacity. The spectral properties of these lower cloud particles are possibly consistent with a component of water ice. The upper cloud particles need a distinct absorption band near 3 $μ$m, possibly consistent with a component of ammonia ice. We note that we do not need a separate upper-level photochemical haze in our model. Instead, we find that the features seen at methane-absorbing wavelengths are caused by variations in the opacity and vertical extent of the upper cloud layer.
