%0 Journal Article
%A Schiavon, M.
%A Tampieri, F.
%A Bosveld, F.C.
%A Mazzola, M.
%A Castelli, S. Trini
%A Viola, A.P.
%A Yagüe Anguis, Carlos
%T The share of the mean turbulent kinetic energy in the near-neutral surface layer for high and low wind speeds
%D 2019
%@ 0006-8314
%U https://hdl.handle.net/20.500.14352/13761
%X We examine the dependence on wind speed of the share of the mean turbulent kinetic energy among the three velocity components in the near-neutral surface layer. To contrast the general behaviour and the local effects, four datasets are considered, corresponding to different surfaces and environmental conditions. For high wind speeds (i.e., wind speed ≈ 10 ms^(−1)), the shares are well-defined and about the same for all sites. As wind speed decreases (becoming ≈ 1 ms^(−1)), large record-to-record variability occurs giving, on average, an almost isotropic state for the horizontal velocity components. Through spectral analysis, we relate this behaviour to the low-frequency, submeso motions and to the lack of conditions required by Reynolds averaging. The implications for modelling are also discussed, showing that the wind speed, or a related quantity, must be accounted for, besides stability, in second-order closures.
%~