Identifying coherent structures in stable boundary layer flows

Episodic development of turbulence (also known as ‘bursting') and coherent structures (patchy turbulence) are ubiquitous features of stably stratified flows. These seemingly random yet highly organized features pose great challenges in signal processing. Commonly used spectral techniques are not always sufficient to characterize details in these flow patterns. In this study, we develop a rigorous statistical technique to detect the existence of intermittent high turbulence events which are not captured by standard stationary second-order models. The proposed methodology is based on the concept of an incoherent signal and does not make any assumption about the process spectrum. An extensive collection of field observation data from various campaigns is used to corroborate the potential of our coherent structure detection methodology with high statistical confidence.