scholarly journals Nondimensional Wind and Temperature Profiles in the Atmospheric Surface Layer over the Hinterland of the Taklimakan Desert in China

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yongqiang Liu ◽  
Ali Mamtimin ◽  
Wen Huo ◽  
Xinghua Yang ◽  
Xinchun Liu ◽  
...  
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
Stable Stratification ◽  
Taklimakan Desert ◽  
Temperature Profiles ◽  
The Taklimakan Desert ◽  
Arid Desert ◽  
Neutral Conditions ◽  
Good Agreement ◽  
Neutral Stratification

Observed turbulent fluxes, wind, and temperature profiles at Tazhong station over the hinterland of the Taklimakan Desert in China have been analyzed to evaluate empirical parameters used in the profile functions of desert surface layer. The von Kármán constant derived from our observations is about 0.396 in near-neutral stratification, which is in good agreement with many other studies for different underlying surface. In our analysis, the turbulent Prandtl number is about 0.75 in near-neutral conditions. For unstable range, the nondimensional wind and temperature profile functions are best fitted by the exponents of −1/4 and −1/2, respectively. The linear relations still hold for stable stratification in this extremely arid desert. However, the parameters used in their profile functions need to be revised to be applicable for desert surfaces.

scholarly journals A Spectral Budget Model for the Longitudinal Turbulent Velocity in the Stable Atmospheric Surface Layer

2015 ◽  
Vol 73 (1) ◽  
pp. 145-166 ◽  
Author(s):  
Tirtha Banerjee ◽  
Dan Li ◽  
Jehn-Yih Juang ◽  
Gabriel Katul
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
Longitudinal Velocity ◽  
Turbulent Velocity ◽  
Correction Function ◽  
Inertial Subrange ◽  
Temperature Profiles ◽  
Budget Model ◽  
The Mean ◽  
The Stability

Abstract A spectral budget model is developed to describe the scaling behavior of the longitudinal turbulent velocity variance with the stability parameter and the normalized height in an idealized stably stratified atmospheric surface layer (ASL), where z is the height from the surface, L is the Obukhov length, and δ is the boundary layer height. The proposed framework employs Kolmogorov’s hypothesis for describing the shape of the longitudinal velocity spectra in the inertial subrange, Heisenberg’s eddy viscosity as a closure for the pressure redistribution and turbulent transfer terms, and the Monin–Obukhov similarity theory (MOST) scaling for linking the mean longitudinal velocity and temperature profiles to ζ. At a given friction velocity , reduces with increasing ζ as expected. The model is consistent with the disputed z-less stratification when the stability correction function for momentum increases with increasing ζ linearly or as a power law with the exponent exceeding unity. For the Businger–Dyer stability correction function for momentum, which varies linearly with ζ, the limit of the z-less onset is . The proposed framework explains why does not follow MOST scaling even when the mean velocity and temperature profiles may follow MOST in the ASL. It also explains how δ ceases to be a scaling variable in more strongly stable (although well-developed turbulent) ranges.

scholarly journals Comparison of Surface Wind Speed and Wind Speed Profiles in the Taklimakan Desert

2021 ◽  
Author(s):  
Liu Xinchun ◽  
kang yongde ◽  
Chen Hongna ◽  
Lu Hui
Keyword(s):  
Wind Speed ◽  
Hydrological Cycle ◽  
Similarity Theory ◽  
Surface Wind ◽  
Taklimakan Desert ◽  
Diurnal Changes ◽  
Wind Speed Profile ◽  
Near Surface ◽  
The Taklimakan Desert ◽  
Neutral Stratification

Abstract Near-surface (10 m) wind speed (NWS) plays a crucial role in many areas, including the hydrological cycle, wind energy production, and the dispersion of air pollution. Based on wind speed data from Tazhong and the northern margins of the Taklimakan Desert in Xiaotang in spring, summer, autumn, and winter of 2014 and 2015, statistical methods were applied to determine the characteristics of the diurnal changes in wind speed near the ground and the differences in the wind speed profiles between the two sites. The average wind speed on a sunny day increased slowly with height during the day and rapidly at night. At heights below 4 m the wind speed during the day was higher than at night, whereas at 10 m the wind speed was lower during the day than at night. The semi-empirical theory and Monin-Obukhov (M-O) similarity theory were used to fit the NWS profile in the hinterland of the Tazhong Desert. A logarithmic law was applied to the neutral stratification wind speed profile, and an exponential fitting correlation was used for non-neutral stratification. The more unstable the stratification, the smaller the n. Using M-O similarity theory, the “linear to tens of” law was applied to the near-neutral stratification. According to the measured data, the distribution of φM with stability was obtained. The γm was obtained when the near-surface stratum was stable in the hinterland of Tazhong Desert and the βm was obtained when it was unstable. In summer, γm and βm were 5.84 and 15.1, respectively, while in winter, γm and βm were 1.9 and 27.1, respectively.

scholarly journals PIV measurement of buffer and logarithmic layers with detached eddies which mimics the neutral atmospheric surface layer

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yasuo Hattori ◽  
Hitoshi Suto ◽  
Keisuke Nakao ◽  
Hiromaru Hirakuchi
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
Prediction Models ◽  
Weather Prediction ◽  
Long Distance ◽  
Flat Surfaces ◽  
Piv Measurement ◽  
Reynolds Number Effects ◽  
Underlying Surface Conditions ◽  
Neutral Conditions

Accurate comprehension of turbulence characteristics in the atmospheric surface layer (ASL) under near neutral conditions, which is a lower part of the atmospheric boundary layer and a very high-Re number flow, is critically required in view of the increasing and broadening use of numerical weather prediction models. The models need to estimate turbulence fluxes of momentum, heat and moisture in the ASL as boundary conditions. On the other hand, observations (Högström 1990, Drobinski et al. 2007) have revealed that the fluxes under near-neutral conditions are often inconsistent with Monin-Obukhof theory, which has been widely used in models. The observations were conducted over flat surfaces with homogeneous roughness, and thus the violation from the theory might not be due to the underlying surface conditions. Thus, aiming to investigate an origin of the violation from the theory, we have carried out a wind tunnel experiment on the logarithmic layer along a smooth flat wall with a larger-scale disturbance, which mimics the near-neutral atmospheric surface layer (Hattori et al. 2010). In the present study, we especially examine a PIV measurement with a long-distance microscope lens to discuss the interaction of turbulences structures between buffer and logarithmic layers, which must give a clue on Reynolds number effects

Probability law of turbulent kinetic energy in the atmospheric surface layer

2021 ◽  
Vol 6 (7) ◽  
Author(s):  
Mohammad Allouche ◽  
Gabriel G. Katul ◽  
Jose D. Fuentes ◽  
Elie Bou-Zeid
Keyword(s):  
Surface Layer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Atmospheric Surface Layer
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