Abstract
Surface layer turbulence has an important influence on land-air interactions and pollutant dispersion, and studying the characteristics of surface layer turbulence in complex terrain can contribute to understanding land-air interactions, improving model surface layer parameterization, and enhancing pollution prediction capabilities. The surface layer turbulence observations from the Semi-Arid Climate and Environment Observatory (SACOL) of Lanzhou University in 2008 were processed in this study. High-quality turbulence parameters were calculated, the statistical and transfer characteristics of turbulence were analyzed, and the formation of turbulence was assessed in terms of dynamics and thermodynamics. The atmospheric stability in the semiarid region of the Loess Plateau is basically dominated by neutral/near-neutral and weakly unstable/weakly stable conditions; this pattern is significantly different from the preponderance of unstable and stable layers at other sites. The turbulence intensity differs significantly in both the horizontal and vertical directions and basically shows the relationship I u ≈ I v > I w . The mean values of I u and I v are 0.42 and 0.40, respectively, and the mean value of I w is 0.14, which is different from the general pattern of I u > I v > I w , indicating that the turbulence intensity at SACOL is characterized by a large lateral wind contribution. The dimensionless standard deviations of the nonneutral wind velocity components satisfy the “1/3rd law,” and the dimensionless standard deviations of u, v , and w components are 3.35, 2.98, and 1.26, respectively, in the semiarid Loess Plateau. These values are larger than those over flat terrain. The contribution of the shear term to the formation of turbulence is greater than that of the buoyancy term, and the mean annual values of the shear term and the buoyancy in the kinetic energy budget equation in SACOL are 47.94 × 10−4 m2·s−3 and 11.32 × 10−4 m2·s−3, respectively. The annual mean values of the momentum transfer coefficient C D and the heat transfer coefficient C H under near-neutral conditions are 8.54 × 10−3 and 2.52 × 10−3, respectively.
Highlights
Surface layer turbulence has an important influence on land-air interactions and pollutant dispersion, and studying the characteristics of surface layer turbulence in complex terrain can contribute to understanding land-air interactions, improving model surface layer parameterization, and enhancing pollution prediction capabilities. e surface layer turbulence observations from the Semi-Arid Climate and Environment Observatory (SACOL) of Lanzhou University in 2008 were processed in this study
Martins et al [12] observed the standard deviations of velocities and temperature fluctuations at the edge of a sharp cliff, suggesting that complex topography causes quasimesoscale motions, such as gravity waves and local circulation, which change the structure of the turbulence. de Franceschi et al [13] fitted the empirical coefficient with along-valley and cross-valley winds for u, v, w, and θ, respectively, and confirmed the validity of Monin-Obukhov similarity theory (MOST) over both stability ranges and for all wind velocity components
Conclusions e eddy covariance (EC) and boundary layer gradient observatory tower data from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) were processed with the EC method for quality control and data processing to obtain the statistical parameters of the surface layer turbulence in order to analyze the turbulence characteristics of the complex terrain in the semiarid zone of the Loess Plateau. e formation of turbulence in terms of dynamics and thermal conditions is discussed in this study. e main results are summarized as follows
Summary
Surface layer turbulence has an important influence on land-air interactions and pollutant dispersion, and studying the characteristics of surface layer turbulence in complex terrain can contribute to understanding land-air interactions, improving model surface layer parameterization, and enhancing pollution prediction capabilities. e surface layer turbulence observations from the Semi-Arid Climate and Environment Observatory (SACOL) of Lanzhou University in 2008 were processed in this study. Surface layer turbulence has an important influence on land-air interactions and pollutant dispersion, and studying the characteristics of surface layer turbulence in complex terrain can contribute to understanding land-air interactions, improving model surface layer parameterization, and enhancing pollution prediction capabilities. Erefore, an in-depth study of the turbulence characteristics in the atmospheric boundary layer, especially in the surface layer, is important for understanding land-air interactions, improving the model’s performance over complex terrain, improving air pollution prediction, and the efficient use of wind energy. Study on characteristics of surface layer turbulence in complex terrain as the Loess Plateau, the similarity of variance relationships in typical complex terrain, the thermal and dynamic contributions of turbulent kinetic energy, and transfer characteristics is demanded. Further research is needed on the similarity in the variance characteristics of turbulence influenced by the complex topography of the Loess Plateau region and the dynamics and thermal contributions of turbulence formation. A systematic understanding of surface layer turbulence in the Loess Plateau region will help to provide a parameterization of the surface layer material and energy transfer processes on the complex underlying surface of the Loess Plateau region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
