logarithmic layer*

We present super-large-scale particle image velocimetry (SLPIV) measurements in the thermally-neutral atmospheric surface layer. The field site represents a canonical fully rough wall boundary layer with a Reynolds number of the order Re_τ∼10⁶. The measurements capture the lowest 20 m of the surface layer and include the bottom of the logarithmic region. Structural features of the boundary layer observed in previous laboratory PIV studies are similarly present in our results at the atmospheric scale. We use the spatio-temporal SLPIV data to describe the spatial organization of wall turbulence in terms of vortex structures, zones of uniform momentum (UMZs), and internal shear layers. We compare the properties and wall-normal trends of these features to the characteristic scales of the logarithmic region, namely the friction velocity and the wall-normal distance. We discuss the findings in the context of existing theory such as the attached eddy hypothesis.