Investigation into Variations of Wind Directions Near the Surface

The results of a full-scale experiment carried out at the Obukhov Institute of Atmospheric Physics testing ground in Tsimlyansk in 2015 are described. The experiment included multipoint measurements of wind variations using 12 vanes arranged in a line across (and in some cases lengthwise) the wind directions. The correlation functions were used to calculate longitudinal and transversal correlation radii, which characterized, accordingly, the longitudinal and transversal dimensions of vortices in the airflow. The longitudinal radius was 1.8 times the transversal radius. The correlation radius dependence on the scale of Obukhov-Monin surface layer was obtained. The maxima of transversal correlation radius (about 20 m) were observed at daytime with great instability. At night they were a few times lower. Wind pulsation spectra depend on the thermal stratification and the mean wind velocity. The technique proposed in the paper allows studying the spatial structure of the direction field of the surface wind.