The Ratio of the Second and Third Turbulent Moments in the Urban Boundary Layer of the Atmosphere on the Example of Data from the Moscow State University Eddy Covariance Tower

Abstract

This work is devoted to testing the hypothesis about the presence of a diagnostic connection between the second and third moments of the hydrodynamic quantities \({{c}_{1}}\) and \({{c}_{2}}\) in the atmospheric boundary layer above a geometrically complex surface: \(\overline {w{\kern 1pt} 'c_{1}^{'}c_{2}^{'}} = C{{S}_{{{{c}_{1}}}}}{{\sigma }_{{{{c}_{1}}}}}\overline {w{\kern 1pt} 'c_{2}^{'}} .\) To test this ratio, a seven-month series of high-frequency measurements on an eddy covariance tower installed at the Meteorological Observatory of Lomonosov Moscow State University was used. Based on the statistical distribution of the third moments, the optimal methods for analyzing the reliability of the dependence under study were determined. For the first time on a large series of data, a statistically valid assessment of the validity of the tested hypothesis was obtained in the conditions of the urban underlying surface. The influence of stratification conditions and the nature of the underlying surface in the area of flux formation on the fulfillment of ratio second and third moments is studied. It is established that for the third moments \(\overline {w{\kern 1pt} 'w{\kern 1pt} 'T{\kern 1pt} '} ,\) \(\overline {w{\kern 1pt} 'T{\kern 1pt} 'T{\kern 1pt} '} ,\) \(\overline {w{\kern 1pt} 'u{\kern 1pt} 'u{\kern 1pt} '} ,\) and \(\overline {w{\kern 1pt} 'v{\kern 1pt} 'v{\kern 1pt} '} \) relation second and third moments is valid in 80% of cases.