论文标题
在火星时代的高层大气中，禁止的原子氧排放
Forbidden atomic oxygen emissions in the Martian dayside upper atmosphere
论文作者
论文摘要
最近，火星发现（Nomad）紫外线和可见光谱仪仪器的Nadir和掩星同时测量了[OI] 2972和5577Å（绿色）的肢体发射强度，同时测量了Martian上层气氛的日子。我们的目的是在火星日光的上层气氛中探索所有这些禁止的原子氧排放的光化学（[[OI] 2972，5577，6300，6464Å），以及适合同时检测这些排放线的可见光谱中这些排放线的适当条件。开发了一个光化学模型，以研究O（1s）和O（1D）的生产和损失过程，通过在火星上层大气中掺入不同的O含类物种的各种化学反应。通过将FOX（2004）降低中性密度曲线的建模为2倍，发现[OI] 5577和2972Å排放的计算出的肢体强度曲线与nomad-Tgo观测值一致。在这种情况下，在120 km以下的高度下，与[OI]2972Å发射的Nomad-Tgo观察值相比，[OI]6300Å发射的建模肢体强度要小于一个因子2至5，并且在此距离之上，它与观察值的上限相当。我们研究了各种参数，这些参数可以影响这些原子氧的肢体强度。我们计算出的[OI]6300Å发射的肢体强度，当火星处于附近，对于太阳的最大条件，这表明在火星上层大气层的日子里，应观察到所有这些禁止的排放。更同时观察禁止的原子氧发射线将有助于理解含氧物种在时代的火星上层大气中的光化学过程。
Recently, Nadir and Occultation for Mars Discovery (NOMAD) ultraviolet and visible spectrometer instrument on board the European Space Agency's ExoMars Trace Gas Orbiter (TGO) simultaneously measured the limb emission intensities for both [OI] 2972 and 5577 Å (green) emissions in the dayside of Martian upper atmosphere. We aim to explore the photochemistry of all these forbidden atomic oxygen emissions ([OI] 2972, 5577, 6300, 6464 Å) in the Martian daylight upper atmosphere and suitable conditions for the simultaneous detection of these emissions lines in the dayside visible spectra. A photochemical model is developed to study the production and loss processes of O(1S) and O(1D) by incorporating various chemical reactions of different O-bearing species in the upper atmosphere of Mars. By reducing Fox (2004) modelled neutral density profiles by a factor of 2, the calculated limb intensity profiles for [OI] 5577 and 2972 Å emissions are found to be consistent with the NOMAD-TGO observations. In this case, at altitudes below 120 km, our modelled limb intensity for [OI] 6300 Å emission is smaller by a factor 2 to 5 compared to that of NOMAD-TGO observation for [OI] 2972 Å emission, and above this distance it is comparable with the upper limit of the observation. We studied various parameters which can influence the limb intensities of these atomic oxygen forbidden emission lines. Our calculated limb intensity for [OI] 6300 Å emission, when the Mars is at near perihelion and for solar maximum condition, suggests that all these forbidden emissions should be observable in the NOMAD-TGO visible spectra taken on the dayside of Martian upper atmosphere. More simultaneous observations of forbidden atomic oxygen emission lines will help to understand the photochemical processes of oxygen-bearing species in the dayside Martian upper atmosphere.
