First Na lidar measurements of turbulence heat flux, thermal diffusivity, and energy dissipation rate in the mesopause region
First Na lidar measurements of turbulence heat flux, thermal diffusivity, and energy dissipation rate in the mesopause region
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首次 Na 激光雷达测量中层顶区域的湍流热通量、热扩散率和能量耗散率
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发表时间：
2017
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通讯作者：
C. Gardner
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作者：
Yafang Guo;A. Liu;C. Gardner
湍流在中层顶区域普遍存在，大气稳定性低，波浪破碎频繁。测量该地区的湍流具有挑战性，传统上是通过火箭探测和雷达来完成的。在这项工作中，我们首次展示了位于智利帕雄山安第斯激光雷达天文台的现代Na风/温度激光雷达能够直接测量85至100公里之间温度和垂直风的湍流扰动。利用 150 小时的激光雷达观测，我们得出了重力波和湍流的频率 (ω) 和垂直波数 (m) 谱，其遵循幂律，斜率与理论模型一致。涡流热通量通常随着高度的增加而减小，从 85 km 处的约 -0.5 Km s−1 到 100 km 处的 -0.1 Km s−1 ，在 93 km 处局部最大值为 -0.6 Km s−1 。得出的平均湍流热扩散率和能量耗散率分别为 43 m2 s−1 和 37 mW kg−1。热传输和能量耗散导致的平均净冷却为-4.9 ± 1.5 K d-1，与-7.9 ± 1.9 K d-1 的重力波传输导致的平均净冷却相当。湍流关键参数与湍流理论一致。
Turbulence is ubiquitous in the mesopause region, where the atmospheric stability is low and wave breaking is frequent. Measuring turbulence is challenging in this region and is traditionally done by rocket soundings and radars. In this work, we show for the first time that the modern Na wind/temperature lidar located at Andes Lidar Observatory in Cerro Pachón, Chile, is able to directly measure the turbulence perturbations in temperature and vertical wind between 85 and 100 km. Using 150 h of lidar observations, we derived the frequency (ω) and vertical wave number (m) spectra for both gravity wave and turbulence, which follow the power law with slopes consistent with theoretical models. The eddy heat flux generally decreases with altitude from about −0.5 Km s−1 at 85 km to −0.1 Km s−1 at 100 km, with a local maximum of −0.6 Km s−1 at 93 km. The derived mean turbulence thermal diffusivity and energy dissipation rate are 43 m2 s−1 and 37 mW kg−1, respectively. The mean net cooling resulted from the heat transport and energy dissipation is −4.9 ± 1.5 K d−1, comparable to that due to gravity wave transport at −7.9 ± 1.9 K d−1. Turbulence key parameters show consistency with turbulence theories.