On the Structure of the Turbulent Field in the Surface Boundary Layer

Analysis of the Data Obtained at O'Neill, Nebraska

Abstract

In order to obtain more information about the structure of the surface boundary layerin the atmosphere, especially in thermally stratified conditions, analyses of the data obtained at O'Neill, Nebraska are conducted. From the viewpoint of the similarity theory developed by the Russian meteorologists, the fundamental coefficients such as (∂U/∂logz)z=0, (∂T/∂logz)z=0, roughness parameter and others are determined graphically, considering that the profiles of wind speed and temperature are subject to the "log+linear" law. Then the fundamental parameters such as the friction velocity, the friction temperature, and the stability are calculated. The physical quantities derived from the fundamental coefficients, such as the shearing stress and the turbulent heat flux, are compared with the observed, values. Then the relationship between the structure of the turbulence and the stability is studied.
Results are as follows: (1) The similarity theory holds. If the "constant" of the linear term is assumed to change with the stability, the "log+ linear" law is considered to hold over a wide range of stability. The calculated values of the shearing stress and the turbulent heat flux are fairly agreeable. (2) Every physical quantity is considered to be arranged only by the fundamental parameters (or the fundamental coefficients, that is, the profiles of wind speed and temperature). For instance, the power index in the "power" law, the standard deviation of wind speed divided by the friction velocity, the standard deviation of azimuthal angle and the relation of the nondimensional spectral density to the nondimensional frequency can be adjusted by the stability which is represented by the height divided by the stability length.