Características espectrais e similaridade da camada limite superficial sobre terreno complexo
In this work it is investigated the turbulence characteristics of the surface boundary layer in conditions of not space homogeneity.
The main of the work is to analyze the turbulence intensity and the spectra of the vertical velocity component in terms of the Monin-Obukhov similarity theory. The results are also compared with those obtained in conditions of space homogeneity.
The turbulence data were obtained in two fields campaigns accomplished in a region of complex topography. A 12 m micrometeorological tower equipped with fast and slow response sensors was used in both experiments.
The nondimensional functions, φw = σw / u* , φθ = σθ / |T* | and φε = kzε / u3* , did not present a consistent dependence with z/L. Suggesting that local scales should be used for their normalization.The normalized spectrum of the vertical velocity component, fSw( f ) /u²*φ2/3ε, was analyzed, for several z/L values in function of the frequency adimensional n = fz /ū . In the high frequency side the spectra converge to a single universal curve that obey the n-2/3 law. However, in the low frequencies side it is not observed a clear separation of the spectra with z/L values.
KAIMAL, J. C.; FINNIGAN, J. J., 1994. Atmospheric Boundary Layer Flows – Their Structure and Measurement. Oxford University Press, NY, 289 pp.
KOLMOGOROV, A. N., 1941. The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers. Doklady ANSSSR. v.30, 301-304.
MONIN, A. S., OBUKHOV, A. M. 1954. Basic laws of turbulent mixing in the ground layer of the atmosphere. Trans. Geophys. Inst. Akad. Nauk. USSR. v.151, 163-187.
SORBJAN, Z., 1989. Structure of the Atmospheric Boundary Layer. PrenticeHall, Englewood Cliffs, NJ, 317 pp.
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