Schiavon, M.Tampieri, F.Bosveld, F.C.Mazzola, M.Castelli, S. TriniViola, A.P.Yagüe Anguis, Carlos2023-06-172023-06-172019-070006-831410.1007/s10546-019-00435-6https://hdl.handle.net/20.500.14352/13761© Springer Nature B.V. 2019. Thanks are due to: the SABLES98 team, Prof. J.L. Casanova (Director of CIBA), and Dr. J. Peláez (for his technical support); the Korean Polar Research Institute (KOPRI), in particular Dr. T. Choi, that provided CSAT3 CCT sonic data. CY has been funded by the Spanish Government, under MINECO projects CGL2015-65627-C3-3-R (MINECO/FEDER) and CGL2016-81828-REDT.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.engjournal articlehttp://dx.doi.org/10.1007/s10546-019-00435-6https://link.springer.com/open access52Stable boundary-layerFlux-profile relationshipsSimilarity theoryStandard deviationsClosure-modelSpectraTemperatureParametersRegimesFísica atmosférica2501 Ciencias de la Atmósfera