Scaling Of Wall-normal Turbulence Intensity And Vertical Eddy Structures In The Atmospheric Surface Layer

Adequate high-quality data on three-dimensional velocities in the atmospheric surface layer(ASL)were acquired in the field at the Qingtu Lake Observation Array(QLOA).The measurement range occupies nearly the entire logarithmic layer from approximately 0.006? to 0.2?.The turbulence intensity and eddy structures of the velocity fluctuations in the logarithmic region were primarily analysed,and their variations in the z(wall-normal)direction were revealed.The primary finding was that the turbulent intensity of wall-normal velocity fluctuations exhibits a sharp upswing in the logarithmic region,which differs from classic scaling law and laboratory results.The upswing of the wall-normal turbulence intensity in the logarithmic region is deemed to be linear based on an ensemble of 20 sets of data.Streamwise and spanwise turbulence intensity in the logarithmic region both show logarithmic linear relationship and Reynolds number effect.We analysed the wall-normal extent of the correlated structures and wall-normal spectra as well and the results were compared to low Reynolds number results in the laboratory.The vortes structures of streamwise and spanwise are “attached”,implying that they are always present in log region while vortes structures of wall-normal are “detached”,implying that there are almost absent or just a few of structures near the wall and as the heights increases,these structures gradually increase and become important.In addition,the uncertainty of the data and the influence of several factors on the results are also analysed.