Print Email Facebook Twitter A Businger Mechanism for Intermittent Bursting in the Stable Boundary Layer Title A Businger Mechanism for Intermittent Bursting in the Stable Boundary Layer Author van der Linden, S.J.A. (TU Delft Atmospheric Remote Sensing) van de Wiel, B.J.H. (TU Delft Atmospheric Remote Sensing) Petenko, Igor (National Research Council; A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences) van Heerwaarden, Chiel C. (Wageningen University & Research) Baas, P. (TU Delft Atmospheric Remote Sensing) Jonker, H.J.J. (TU Delft Atmospheric Remote Sensing) Date 2020 Abstract High-resolution large-eddy simulations of the Antarctic very stable boundary layer reveal a mechanism for systematic and periodic intermittent bursting. A nonbursting state with a boundary layer height of just 3 m is alternated by a bursting state with a height of ≈5 m. The bursts result from unstable wave growth triggered by a shear-generated Kelvin–Helmholtz instability, as confirmed by linear stability analysis. The shear at the top of the boundary layer is built up by two processes. The upper, quasi-laminar layer accelerates due to the combined effect of the pressure force and rotation by the Coriolis force, while the lower layer decelerates by turbulent friction. During the burst, this shear is eroded and the initial cause of the instability is removed. Subsequently, the interfacial shear builds up again, causing the entire sequence to repeat itself with a time scale of ≈10 min. Despite the clear intermittent bursting, the overall change of the mean wind profile is remarkably small during the cycle. This enables such a fast erosion and recovery of the shear. This mechanism for cyclic bursting is remarkably similar to the mechanism hypothesized by Businger in 1973, with one key difference. Whereas Businger proposes that the flow acceleration in the upper layer results from downward turbulent transfer of high-momentum flow, the current results indicate no turbulent activity in the upper layer, hence requiring another source of momentum. Finally, it would be interesting to construct a climatology of shear-generated intermittency in relation to large-scale conditions to assess the generality of this Businger mechanism. To reference this document use: http://resolver.tudelft.nl/uuid:542a97fb-7e3b-4e19-9c22-92dc193662c9 DOI https://doi.org/10.1175/JAS-D-19-0309.1 ISSN 0022-4928 Source Journal of the Atmospheric Sciences, 77 (10), 3343-3360 Part of collection Institutional Repository Document type journal article Rights © 2020 S.J.A. van der Linden, B.J.H. van de Wiel, Igor Petenko, Chiel C. van Heerwaarden, P. Baas, H.J.J. Jonker Files PDF jasd190309.pdf 1.88 MB Close viewer /islandora/object/uuid:542a97fb-7e3b-4e19-9c22-92dc193662c9/datastream/OBJ/view