GrAnd-scale Imaging Apparatus (GAIA) and wind LiDAR multi-scale turbulence measurements in the atmospheric surface layer*

Understanding the organization and dynamics of turbulence structures in the atmospheric surface layer (ASL) is important for many scientific and technical research thrust areas, including particle transport, natural hazards, agriculture, meteorology, and wind energy. A better understanding of ASL flows is important to improve wall models for large-eddy simulations, numerical weather prediction and snow settling models, all of which must take into account the spatio-temporal heterogeneity and the multi-scale nature of ASL flows. To tackle the foregoing challenges, a grand-scale atmospheric imaging apparatus (GAIA) has been developed to perform particle image velocimetry (PIV) in the lowest part of the ASL with a high spatio-temporal resolution, which is coupled with two scanning Doppler wind LiDARs to achieve unprecedented coverage of spatial flow scales from 10^-1 m up to 10³ m. The field campaign and preliminary results are presented focusing on observations of complex flow scenarios, such as the modulation induced by larger flow structures, which are probed through the wind LiDARs, on the morphology, dynamics, and energy content of small-scale turbulence closer to the ground measured through the GAIA PIV.