Statistical characterization of high-to-medium frequency mesoscale gravity waves by lidar-measured vertical winds and temperatures in the MLT
Statistical characterization of high-to-medium frequency mesoscale gravity waves by lidar-measured vertical winds and temperatures in the MLT
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MLT 中激光雷达测量的垂直风和温度对高中频中尺度重力波的统计特征
DOI：
10.1016/j.jastp.2016.10.009
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发表时间：
2017
影响因子：
1.9
通讯作者：
S. Vadas
中科院分区：
文献类型：
--
作者：
Xian Lu;X. Chu;Haoyu Li;Cao Chen;John A. Smith;S. Vadas
我们提出了第一个统计研究的重力波的周期为0.3-2.5小时，是持续的和占主导地位的垂直风与科罗拉多大学星星钠多普勒激光雷达在博尔德，CO（40.1° N，105.2° W）测量。直接从观测资料中导出了温度波和垂直风波振幅的概率密度函数、两种振幅的比值、它们之间的相位差和垂直波长。每个波的固有周期和水平波长推断其垂直波长，振幅比，和指定的涡动粘度通过应用重力波偏振和色散关系。振幅比与地基周期呈正相关，相关系数约为0.76。垂直风和温度之间的相位差（φ W− φ T）遵循高斯分布，为84.2±26.7°，这比非耗散波预测的标准差（~ 3.3°）大得多。对于非耗散波，观测到的相位差与其预测值的偏差可以指示波耗散。垂直波长较短的波往往有较大的相位差偏差，这意味着耗散效应是更短的波更显着。这些波的垂直波长大多数在5至40公里之间，平均值和标准差分别为~ 18.6和7.2公里。对于周期相似的波浪，垂直波长上的多个峰值经常被识别出来，并且在统计上，垂直风中的峰值比温度中的峰值要长。水平波长大多在50至500公里之间，平均值和中值分别为~ 180和125公里。因此，这些波是具有高到中等频率的中尺度波。由于它们最近在高分辨率大气环流模式（GCM）中变得可分辨，因此本统计研究为它们提供了重要和及时的参考。
We present the first statistical study of gravity waves with periods of 0.3–2.5 h that are persistent and dominant in the vertical winds measured with the University of Colorado STAR Na Doppler lidar in Boulder, CO (40.1° N, 105.2° W). The probability density functions of the wave amplitudes in temperature and vertical wind, ratios of these two amplitudes, phase differences between them, and vertical wavelengths are derived directly from the observations. The intrinsic period and horizontal wavelength of each wave are inferred from its vertical wavelength, amplitude ratio, and a designated eddy viscosity by applying the gravity wave polarization and dispersion relations. The amplitude ratios are positively correlated with the ground-based periods with a coefficient of~ 0.76. The phase differences between the vertical winds and temperatures (φ W− φ T) follow a Gaussian distribution with 84.2±26.7°, which has a much larger standard deviation than that predicted for non-dissipative waves (~ 3.3°). The deviations of the observed phase differences from their predicted values for non-dissipative waves may indicate wave dissipation. The shorter-vertical-wavelength waves tend to have larger phase difference deviations, implying that the dissipative effects are more significant for shorter waves. The majority of these waves have the vertical wavelengths ranging from 5 to 40 km with a mean and standard deviation of~ 18.6 and 7.2 km, respectively. For waves with similar periods, multiple peaks in the vertical wavelengths are identified frequently and the ones peaking in the vertical wind are statistically longer than those peaking in the temperature. The horizontal wavelengths range mostly from 50 to 500 km with a mean and median of~ 180 and 125 km, respectively. Therefore, these waves are mesoscale waves with high-to-medium frequencies. Since they have recently become resolvable in high-resolution general circulation models (GCMs), this statistical study provides an important and timely reference for them.