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首页> 外文期刊>Journal of geophysical research. Planets >Estimation of changes in the composition of the Martian atmosphere caused by CO_2 condensation fromGRS Ar measurements and its application to the rederivation of MGS radio occultationmeasurements
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Estimation of changes in the composition of the Martian atmosphere caused by CO_2 condensation fromGRS Ar measurements and its application to the rederivation of MGS radio occultationmeasurements

机译：利用GRS Ar测量估算CO_2凝结引起的火星大气成分的变化及其在MGS无线电掩星测量中的应用。

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摘要

We propose a method to estimate seasonal changes in the composition of the Martian atmosphere, which is influenced by CO_2 condensation due to the polar nights at southern high latitudes. The method relies on measurements of the Ar concentration obtained by the Gamma Ray Spectrometer(GRS) onboard Mars Odyssey. We assume that the Martian atmosphere is composed of CO_2, N_2, and Ar, and is vertically well mixed. Since N_2 and Ar do not condense even during the polar nights, the ratio of N_2 and Ar remains constant, and the concentrations of N_2 and CO_2 can be estimated from Ar measurements. Estimates of the atmospheric composition were utilized for the rederivation of temperature and pressure profiles in the Mars Global Surveyor (MGS) radio occultation measurements (～70 profiles of ～20,000 profiles in the whole data set) at southern polar latitudes (90?S–75?S) during the autumn, winter, and spring seasons(Ls = 0?–240?). The rederived profiles indicated that use of the standard global composition overestimated the temperature by at least approximately 5 K at Ls = ～ 120? (midwinter), when the largest CO_2 depletion occurred and the CO_2 volume mixing ratio fell to 78%. The occurrence and degree of CO_2 supersaturation were several times higher and larger, respectively, in the rederived temperature profiles than in the original MGS profiles. This suggests that consideration of CO_2 depletion during southern polar nights is needed when studying CO_2 supersaturation using radio occultation profiles.
机译：我们提出了一种方法来估算火星大气成分的季节性变化，该变化受南部高纬度地区极夜造成的CO_2凝结的影响。该方法依赖于火星奥德赛船上伽玛射线光谱仪（GRS）获得的Ar浓度的测量值。我们假设火星大气层由CO_2，N_2和Ar组成，并且垂直混合良好。由于N_2和Ar即使在极夜也不会凝结，因此N_2和Ar的比例保持恒定，并且可以通过Ar测量来估算N_2和CO_2的浓度。在南极纬度（90？S–75）的火星全球测量师（MGS）无线电掩星测量（整个数据集中约70个〜20,000个剖面中的70个剖面）中，利用大气成分的估计来重新确定温度和压力剖面。 ？S）在秋季，冬季和春季（Ls = 0？–240？）。重新测量的曲线表明，在Ls =〜120？时，使用标准的整体成分会高估温度至少约5K。 （冬季），当发生最大的CO_2消耗并且CO_2体积混合比降至78％时。再加温的温度曲线中，CO_2过饱和的发生和程度分别比原始的MGS曲线高几倍和更大。这表明在使用无线电掩星剖面研究CO_2过饱和时，需要考虑南极夜间的CO_2消耗。

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