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

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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.