Mars ozone measurements near the 1995 aphelion: Hubble space telescope ultraviolet spectroscopy with the faint object spectrograph
Mars ozone measurements near the 1995 aphelion: Hubble space telescope ultraviolet spectroscopy with the faint object spectrograph
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1995 年远日点附近的火星臭氧测量：哈勃太空望远镜紫外光谱与微弱天体摄谱仪
DOI：
10.1029/96je00835
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
M. Callan
中科院分区：
文献类型：
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作者：
R. Clancy;M. Wolff;P. James;E. Smith;Y. Billawala;Steven W. Lee;M. Callan
1995 年 2 月，哈勃太空望远镜 (HST) 微弱天体摄谱仪 (FOS) 获得了火星的紫外（225–330 nm）光谱扫描。这些光谱可得出火星上臭氧柱丰度、云不透明度（低纬度为 0.2–0.4）以及从火星南部中纬度到北部高纬度的极地季节性冰反照率。在进行这些测量时，火星的太阳经度 (Ls) 为 63.5°，对应于火星的北春季末，并且非常接近火星远日点。这些观测最重要的结果是低纬度臭氧丰度 (3.1−0.5+2.1) 的测量，相对于 Espenak 等人的北部秋季（Ls = 208°，近日点前）红外臭氧测量值显着升高（≥100%）。 [1991] 1988 年。全球火星臭氧柱隐含的近日点到远日点的增加（从 1.5−1.0+0.4 到 3.1−0.5+2.1 μm atm）在数量上与 Clancy 和 Nair 的光化学模型分析一致[本期]，该分析预测由于火星上全球水蒸气饱和高度的轨道强迫，火星光化学的年度变化很大[Clancy 等人， 1996]。然而，HST FOS 观测结果并不能诊断火星臭氧密度随 Ls 变化的高度，而这是 Clancy 和 Nair 模型预测的一个关键方面。此外，不确定的臭氧密度分布导致了衍生的 FOS 和 IR 臭氧柱中存在很大的不对称不确定性。在北高纬度地区 (71–75°N) 检索到 7.3 ± 2.5 μm atm 的臭氧柱。推导出的北极季节性二氧化碳冰盖的紫外线反照率是0.18±0.07，大约是火星硅酸盐表面紫外线反照率的10倍，但只有季节性二氧化碳冰盖可见反照率的四分之一。
Ultraviolet (225–330 nm) spectral scans of Mars were obtained with the Hubble space telescope (HST) faint object spectrograph (FOS) in February of 1995. These spectra yield ozone column abundances, cloud opacities (0.2–0.4 at low latitudes), and polar seasonal ice albedos from southern midlatitudes to northern high latitudes on Mars. At the time of these measurements, Mars was at a solar longitude (Ls) of 63.5°, corresponding to the late northern spring season on Mars, and very near to Mars aphelion. The most important result of these observations is the measurement of low-latitude ozone abundances (3.1−0.5+2.1), which are significantly (≥100%) elevated relative to the northern fall (Ls = 208°, pre-perihelion) IR ozone measurements of Espenak et al. [1991] in 1988. The implied perihelion-to-aphelion increase in the global Mars ozone column (from 1.5−1.0+0.4 to 3.1−0.5+2.1 μm atm) is quantitatively consistent with photochemical modeling analysis of Clancy and Nair [this issue], which predicts large annual variations in Mars photochemistry due to orbital forcing of the altitude of global water vapor saturation on Mars [Clancy et al., 1996]. However, the HST FOS observations are not diagnostic of the altitudes at which Mars ozone densities vary with Ls, which is a key aspect of the Clancy and Nair model prediction. Furthermore, it is the uncertain ozone density profile which leads to the large asymmetric uncertainties in the derived FOS and IR ozone columns. An ozone column of 7.3 ± 2.5 μm atm is retrieved for a high northern latitude region (71–75°N). The derived ultraviolet albedo of the north polar seasonal CO2 cap is 0.18 ± 0.07, which is roughly 10 times the ultraviolet albedo of the silicate surface of Mars, but only one quarter the visible albedo of the seasonal CO2 ice cap.