OH and OI airglow layer modulation by ducted short‐period gravity waves: Effects of trapping altitude
OH and OI airglow layer modulation by ducted short‐period gravity waves: Effects of trapping altitude
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DOI：
10.1029/2009ja015236
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发表时间：
2010-11
影响因子：
--
通讯作者：
J. Snively;V. Pasko;M. Taylor
中科院分区：
文献类型：
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作者：
J. Snively;V. Pasko;M. Taylor
[1] 使用二维数值模型研究了 Brunt-Vaisala 周期附近的管道重力波对 OH 和 OI [O(1S) 557.7 nm] 气辉层的扰动。这些波的气辉特征很大程度上取决于 O、O3 和 H 的扰动，这些扰动在中层顶附近和上方表现出峰值密度。短周期重力波的强周期性垂直风分量在层密度峰值上方和下方引起相反的相对密度扰动。管道波的气辉特征取决于波包相对于周围物种密度分布的特定垂直形状和高度；仅扰动层的底部或顶部的波产生的特征不同于那些能够扰动整个层厚度的波。即使对于没有垂直相位级数的驻波，视线抵消也会发生在气辉层峰值上方和下方的相反扰动之间。因此，根据波包相对于密度梯度的高度，集成的亮度加权温度和强度对于驻波可以表现为同相或反相。 OH 和 OI 层强度的比较还揭示了同相或反相相对强度响应，并且不直接指示层峰值高度处的波扰动的相位。尽管存在这种模糊性，同步亮度加权温度测量可以提供对波结构、振幅和捕获高度的额外了解。对于扰乱陡密度梯度的足够振幅的波，可以观察到气辉响应的非线性；当线性特征发生强烈抵消时，这种效应最为突出。
[1] Perturbations to the OH and OI [O(1S) 557.7 nm] airglow layers by ducted gravity waves near the Brunt-Vaisala period are investigated using a 2-D numerical model. Airglow signatures of these waves are strongly determined by perturbations of O, O3, and H, which exhibit peak densities near and above mesopause. Strong periodic vertical wind components of short-period gravity waves induce opposite relative density perturbations above and below the layer density peaks. Airglow signatures for ducted waves depend on the specific vertical shapes and altitudes of the wave packets relative to ambient species density profiles; waves perturbing only the bottoms or tops of the layers produce signatures differing from those able to perturb the entire layer thickness. Line-of-sight cancellation occurs between opposite perturbations above and below airglow layer peaks, even for standing waves without vertical phase progression. Integrated brightness-weighted temperature and intensity can thus appear in-phase or antiphase for standing waves, depending on the wave-packet altitude relative to the density gradients. Comparisons of OH and OI layer intensities also reveal in-phase or antiphase relative intensity responses and do not directly indicate the phase of the wave perturbations at layer peak altitudes. Despite this ambiguity, simultaneous brightness-weighted temperature measurements may provide additional insight into wave structure, amplitude, and trapping altitude. For waves of sufficient amplitude that perturb steep density gradients, nonlinearity of the airglow response may be observable; this effect is most prominent when strong cancellation of the linear signature occurs.