Acoustic remote sensing study of the influence of internal gravity waves on the lower atmosphere

人们认识到，由各种随机源产生的大气重力内波(IGW)在广泛的时间和空间尺度上对大气边界层(ABL)中的风速和温度波动的功率谱有重要贡献。然而，尽管由IGW引起的风速和温度波动的统计特征被发现对稳定的高层大气环流的动力学和湍流状况起着重要的作用，但这些统计特征还没有得到很好的研究。拟议项目的主要目标是利用大气IGW固有的时空尺度调查大气边界层中尺度风速和温度波动的空间结构和统计特征。1)稳定层结条件下中尺度风速和温度起伏对声信号传播参数影响的实验研究：2)利用声层析结合垂直声测深测量稳定层结条件下大气环流中尺度风速和温度的波动。为了解决这些问题，提出了一种新的方法，该方法综合使用了不同的声层析成像方案(水平和垂直切片方案)和附加的ABL垂直声测深。这些声学遥感方法相辅相成，可以重建大气边界层水平切片(300×300 QM)和垂直切片(离地面300米)内的风速和温度场。所得结果将填补我们对中尺度大气湍流性质认识的一个空白，并将有助于大气环流和大气污染输送模式中稳定大气边界层的参数化。

It is recognized that atmospheric internal gravity waves (IGW) generated from various random sources significantly contribute to the power spectrum of the wind speed and temperature fluctuations in the Atmospheric Boundary Layer (ABL) within a broad range of time and spatial scales. However, the statistical characteristics of the wind speed and temperature fluctuations induced by IGWs are not well studied, although these fluctuations were found to play a substantial role in the dynamics and turbulent regime of the stable ABL. The main objective of the proposed project is to investigate the spatial structure and statistical characteristics of the meso-scale wind speed and temperature fluctuations in the ABL with the space-time scales inherent to atmospheric IGWs. For this purpose the following tasks are outlined in the project: 1) The experimental study of the effects of meso-scale wind speed and temperature fluctuations on the parameters of the acoustic signals propagating under stable conditions of the ABL: 2) The measurement of meso-scale fluctuations of wind speed and temperature by means of acoustic tomography combined with vertical acoustic sounding of the ABL under stable stratification of the ABL. To solve these tasks a new approach is proposed based on a combined use of different schemes of acoustic tomography (horizontal and vertical slice schemes) and of additional vertical acoustic sounding of the ABL. These acoustic remote sensing methods complement each other and allow to reconstruct the wind speed and temperature fields within both horizontal slices (300 x 300 qm) and vertical slices (300 m above surface) of the ABL. The results obtained will fill a gap in our knowledge of the properties of meso-scale atmospheric turbulence and will help to parameterize stable ABL in general circulation and air-pollution transport models.