Determination of coefficients in higher-order mean velocity profile in convective atmospheric surface layer using field measurement data

The mean velocity profile in the surface layer of the atmospheric boundary layer is generally considered to follow the Monin-Obukhov similarity at the leading order. However, it is well known that measured mean profiles show deviations from the theory that cannot be explained by measurement uncertainties. To account for these deviations we derived the higher-order mean velocity profile based on the Multipoint Monin-Obukhov Similarity Theory using the method of matched asymptotic expansions. The profile includes additional parameters that quantify the deviations from the Monin-Obukhov Similarity function. In particular, the influence of the boundary layer height is accounted for. To obtain the coefficients in the higher-order terms, data from a field campaign, Multipoint Monin-Obukhov Horizontal ArrayTurbulence Studies (M2HATS), conducted in the summer/fall of 2023 in Tonopah NV are analyzed. Sonic anemometers on towers and two Doppler lidars were deployed to obtain the mean profile up to an approximately 3 km height. The coefficients for the higher-order terms in two scaling regions, the local-free-convection region and the logarithmic region are determined by fitting the expansions to 16 data sets covering a range of non-dimensional parameters. Very good comparisons between the measurement results and the theoretical prediction are obtained. The higher-order expansions provide a new framework to parameterize the mean velocity profile under more general conditions.