Organized Turbulence Structures in the Near-Neutral Atmospheric Surface Layer

Abstract The Tiederman method, which was originally designed for unambiguous detection of “bursts” in the buffer layer of smooth surface laboratory boundary-layer flow, is shown to work equally well in the neutral atmospheric surface layer. It enables estimation of characteristic timescales of significant structures responsible for the momentum transport: mean duration of and mean interval between bursts (upward transport of momentum deficit) and mean duration and interval between sweeps (downward transport of momentum excess). Data representing near neutral conditions from three field experiments over flat and homogeneous areas but with very different roughness characteristics are used in the analysis. For two low vegetation sites (i.e., the measuring heights are very much larger than the roughness sublayer height), it is found that all above-mentioned timescales are constant for any height and identical at the two sites. Scaling the results with the friction velocity indicates the corresponding scaling ...