Structure Functions and Structure Parameters of Velocity Fluctuations in Numerically Simulated Atmospheric Convective Boundary Layer Flows


We extend our previous study, which dealt with structure functions of potential temperature fluctuations, and focus on the characteristics of second-order velocity structure functions and corresponding structure parameters in the atmospheric convective boundary layer. We consider the three previously reported methods to compute the structure parameters of turbulent velocity fields: the direct method, the true spectral method, and the approximate spectral method. The methods are evaluated using high-resolution gridded numerical data from large-eddy simulations of shear-free and shear-driven convective boundary layers. Results indicate that the direct and true spectral methods are more suitable than the approximate spectral method, which overestimates the structure parameters of velocity due to assuming the inertial-subrange shape of the velocity spectrum for all turbulence scales. Results also suggest that structure parameters of vertical velocity fluctuations are of limited utility due to violations of local isotropy, especially in shear-free convective boundary layers.

Journal of the Atmospheric Sciences, 77(10), 3619–3630
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Dr. Jeremy A. Gibbs
Dr. Jeremy A. Gibbs
Research Meteorologist

My name is Jeremy Gibbs. I am a Research Meteorologist at the NOAA National Severe Storms Laboratory. My research includes computational and theoretical studies of atmospheric boundary-layer flows, turbulence modeling, land-surface modeling, parameterization of boundary-layer and surface-layer interactions, and multi-scale numerical weather prediction. I am currently working on projects to improve atmospheric models in the areas of scale-aware boundary-layer physics, heterogeneous boundary layers, and other storm-scale phenomena.