Spectral Composition of Temperature Turbulence for Different Surface Air Layer Stratification Types

Abstract

Parameters of the spectral model of small-scale turbulence are the most important characteristics used to describe the propagation of light and sound in the atmosphere. One of the factors determining the spectral composition of turbulence is the stratification regime. The effect of surface air layer stratification on the deviations of a turbulence spectrum from the Kolmogorov–Obukhov model is studied based on the processing of time series of fluctuations in meteorological parameters recorded by acoustic weather stations. A significant correlation between the stability characteristic (Monin–Obukhov number) and the exponent of the power-law model of the spectrum of temperature fluctuations is found from the comparison of their dynamics. An empirical model of the dependence of the spectrum exponent on the stability characteristic is suggested. The model makes it possible to estimate changes in the parameters of the spectral structure of small-scale turbulence based on estimates of the magnitude and direction of turbulent heat and momentum fluxes. The dependence reflects the features of generation of temperature turbulence under different stratification of the surface air layer. Information on turbulent spectral parameters derived from stratification estimates can be further used to solve problems of optical and acoustic wave propagation and atmospheric sounding.