Radio occultation measurements of forced atmospheric waves on Mars
Radio occultation measurements of forced atmospheric waves on Mars
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火星上强迫大气波的无线电掩星测量
DOI：
10.1029/2000je001291
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
Richard J. Wilson
中科院分区：
文献类型：
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作者：
D. Hinson;G. Tyler;J. Hollingsworth;Richard J. Wilson
火星全球探测者号于1998年12月进行了一系列射电掩星实验，得到了北半球春季末的36个中性大气剖面（Ls = 74.1°–77.3°）。测量结果仅限于纬度（64.6°–67.2°N）和当地时间（0321–0418），但它们在经度上的分布相当均匀。我们使用最小二乘光谱分析来表征大气的纬向结构，并构建了温度和位势的经度-高度横截面。地表附近温度的纬向变化超过 12 K，但在较高海拔处则小得多（2-3 K）。在整个测量的垂直范围内，位势的区域变化约为 200 m。这些温度和位势模式似乎相对于表面是静止的，在 7 个溶胶的测量范围内几乎没有日常变化。我们严重依赖火星大气环流模型（GCM）来指导理解这些数据。静止行星波对温度和位势场的某些方面负责，特别是在压力超过 100-200 Pa 的情况下。根据 GCM 模拟与观测之间的高度相似性，我们得出结论，扰动采取了由 Alba Patera 激发的行星波列的形式。这些数据还包括非太阳同步热潮的特征，当在固定的当地时间采样时，热潮产生的模式似乎是静止的。 GCM 模拟与测量的位势场之间的比较为共振增强的日间波 1 开尔文模式的存在提供了证据。
Mars Global Surveyor performed a series of radio occultation experiments in December 1998, resulting in 36 profiles of the neutral atmosphere in late northern spring (Ls = 74.1°–77.3°). The measurements are confined in latitude (64.6°–67.2°N) and local time (0321–0418), but their distribution in longitude is fairly uniform. We used least squares spectral analysis to characterize the zonal structure of the atmosphere and constructed longitude-height cross sections of both temperature and geopotential. Zonal variations of temperature exceed 12 K near the surface but are much smaller (2–3 K) at higher altitudes. Zonal variations of geopotential are ∼200 m throughout the vertical range of the measurements. These patterns of temperature and geopotential appear to be stationary relative to the surface with little day-to-day variation within the 7-sol span of the measurements. We relied heavily on Mars general circulation models (GCMs) for guidance in understanding these data. Stationary planetary waves are responsible for some aspects of the temperature and geopotential fields, particularly at pressures exceeding 100–200 Pa. On the basis of strong similarities between a GCM simulation and the observations, we conclude that the disturbance takes the form of a planetary wave train excited by Alba Patera. The data also include the signature of non-Sun-synchronous thermal tides, which produce a pattern that appears to be stationary when sampled at fixed local time. Comparison between a GCM simulation and the measured geopotential field provides evidence for the presence of the resonantly enhanced, diurnal, wave-1 Kelvin mode.