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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >WAVE BREAKING SIGNATURES IN SODIUM DENSITIES AND OH NIGHTGLOW .2. SIMULATION OF WAVE AND INSTABILITY STRUCTURES
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WAVE BREAKING SIGNATURES IN SODIUM DENSITIES AND OH NIGHTGLOW .2. SIMULATION OF WAVE AND INSTABILITY STRUCTURES

机译：钠浓度和OH夜光中的波破波信号2。波和不稳定结构的模拟

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Measurements of atmospheric structure and dynamics near the mesopause were performed using a sodium lidar, an MF radar, and a nightglow CCD camera during the CORN campaign performed in central Illinois during September 1992. The major features of the observed structure on September 27/28 include a low-frequency, large-scale wave accounting for persistent overturning of the temperature and sodium density fields, superposed higher-frequency motions, small-scale transient ripples in the nightglow images suggestive of instability structures, and large-scale wind shear near the height of apparent instability. We describe four simulations of wave breaking with a three-dimensional model designed to assist in the interpretation of these observations. Two simulations address the instability of a low-frequency wave in a background shear flow with and without higher-frequency modulation. These show higher-frequency motions to be important in assigning the spatial and temporal scales of instability structures. Two other simulations examine the instabilities accompanying a convectively unstable inertia-gravity wave with and without higher-frequency modulation without mean shear. These show the instability structure to remain aligned in the direction of wave propagation, with only weak influences by the high-frequency motion. Our results suggest that instability due to a superposition of waves accounts best for the nightglow features observed during the CORN campaign and that streamwise convective instabilities observed due to wave breaking at higher intrinsic frequencies continue to dominate instability structure for internal waves for which inertial effects are important. [References: 12]
机译：在1992年9月于伊利诺伊州中部进行的CORN运动期间，使用钠激光雷达，MF雷达和夜光CCD相机对中绝经附近的大气结构和动力学进行了测量。9月27/28日观测到的结构的主要特征包括低频的大尺度波，解释了温度和钠密度场的持续倾覆，叠加的高频运动，夜光图像中的小尺度瞬变波纹（表明不稳定结构）以及高度附近的大规模风切变明显不稳定。我们使用三维模型描述了四个波浪破碎模拟，这些模型旨在帮助解释这些观测结果。有两个模拟解决了在有和没有高频调制的情况下背景剪切流中低频波的不稳定性。这些表明，较高频率的运动对于分配不稳定结构的时空尺度非常重要。另外两个仿真研究了对流不稳定惯性重力波的不稳定性，该惯性重力波在有和没有高频调制且没有平均剪切的情况下进行。这些显示了不稳定性结构在波传播方向上保持对准，而受到高频运动的影响很小。我们的结果表明，由于波的叠加而引起的不稳定性最能解释CORN战役期间观测到的夜光特征，并且由于在较高固有频率处的波破裂而导致的沿流对流不稳定性继续主导着内部波的不稳定性结构，对于这些结构，惯性效应很重要。 [参考：12]

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