Structure functions in nocturnal atmospheric boundary layer turbulence

Turbulence in a nocturnal stably stratified flow draining from a mountain range was captured using a probe system consisting of sonic and hot-film anemometers that communicate with each other through a neural network for optimal operation without any human intervention. This unique `Combo' system allowed probing turbulence continuously down to energy dissipation scales, at Taylor Reynolds number greater than 1200. The data analyses, together with direct numerical simulation, reveal that, contrary to the Kolmogorov Self-Similarity Hypothesis, turbulence at dissipation scales is anisotropic, suggesting a new line of inquiry on turbulence in stable atmospheric boundary layers.