3
Characterization of Turbulent Flow
in the Surface Boundary Layer
Abstract
This chapter aimed to make a characterization of turbulent airflow in the surface
boundary layer, following qualitative and quantitative approaches. The former is
based on a generalization of Navier–Stokes equations, applied to flow mean and
fluctuation components, for obtaining budgets of vectorial and scalar quantities.
The latter is based on similarity relationships dependent on atmospheric stability
for evaluation of the components of kinetic energy budget equations. A spectral
and cospectral frequency characterization of the turbulent flow, aiming to
analyze the spectral structure of production, transport, inertial and dissipative
scales was performed, grounded on a brief introduction on fundamentals of
Fourier analysis. Comparison of measured and calculated spectra following
empirical similarity principles, particularly in slopes of curves in the inertial
region, is fundamental for quality control assessment of atmospheric measurements and for evaluation of turbulent dynamics under distinct atmospheric
stability conditions. The assessment of the power spectrum, autocorrelation, and
cross-correlation functions enhances the potential of frequency analysis of
predominant turbulent eddies. Finally, a discussion is presented about eddy
covariance methodology to obtain vertical fluxes, with measurements of
fluctuations of scalar and vectorial quantities. The methodology is applied
under turbulent transport frequencies, considering quality control proceedings
and applications on local carbon budgets.
3.1 Introduction
As mentioned in previous chapters, atmospheric flows are turbulent in nature.
Flowing fluid moves in a highly disordered and chaotic way, making the velocity
fields difficult to be accurately reproduced under experimental conditions.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
A. Rodrigues et al., Fundamental Principles of Environmental Physics,
https://doi.org/10.1007/978-3-030-69025-0_3
33
Characterization of Turbulent Flow
in the Surface Boundary Layer
Abstract
This chapter aimed to make a characterization of turbulent airflow in the surface
boundary layer, following qualitative and quantitative approaches. The former is
based on a generalization of Navier–Stokes equations, applied to flow mean and
fluctuation components, for obtaining budgets of vectorial and scalar quantities.
The latter is based on similarity relationships dependent on atmospheric stability
for evaluation of the components of kinetic energy budget equations. A spectral
and cospectral frequency characterization of the turbulent flow, aiming to
analyze the spectral structure of production, transport, inertial and dissipative
scales was performed, grounded on a brief introduction on fundamentals of
Fourier analysis. Comparison of measured and calculated spectra following
empirical similarity principles, particularly in slopes of curves in the inertial
region, is fundamental for quality control assessment of atmospheric measurements and for evaluation of turbulent dynamics under distinct atmospheric
stability conditions. The assessment of the power spectrum, autocorrelation, and
cross-correlation functions enhances the potential of frequency analysis of
predominant turbulent eddies. Finally, a discussion is presented about eddy
covariance methodology to obtain vertical fluxes, with measurements of
fluctuations of scalar and vectorial quantities. The methodology is applied
under turbulent transport frequencies, considering quality control proceedings
and applications on local carbon budgets.
3.1 Introduction
As mentioned in previous chapters, atmospheric flows are turbulent in nature.
Flowing fluid moves in a highly disordered and chaotic way, making the velocity
fields difficult to be accurately reproduced under experimental conditions.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
A. Rodrigues et al., Fundamental Principles of Environmental Physics,
https://doi.org/10.1007/978-3-030-69025-0_3
33