A Compensated Structure‐Function Approach to Measuring TKE Dissipation in the Atmospheric Boundary Layer

Abstract Despite the importance of turbulence measurements to atmospheric dynamics and modeling, developing objective, accurate schemes to estimate TKE dissipation ε from velocity time‐series has proven elusive. Objective schemes can be automated, as needed for large data sets generated by today's field programs. But a survey of many such schemes showed that reported approaches are either subjective or rely on assumptions often violated in the real‐world atmosphere. An objective scheme using the compensated structure function is presented, estimating ε and the timescale limits of the turbulence inertial subrange. The procedure is tested using daytime sonic‐anemometer data from Boulder's 300‐m tower. Dissipation profiles were decreasing or nearly constant with height as characteristic of the upper part of unstable surface layers, and magnitudes of 10 −3 –10 −2 m 2 s −3 are also typical of the lower unstable ABL. Results show that, for the midday periods analyzed, a significant fraction of the time‐series variance resides at nonturbulent scales.