Contrasting Vertical Structures of the Stable Boundary Layer

Download or read book Contrasting Vertical Structures of the Stable Boundary Layer written by and published by . This book was released on 2002 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wyngaard (1973) introduced the concept of z-less stratification for cases where the stratification is sufficiently strong, that the turbulence no longer is in significant communication with the surface (see also Holtslag and Nieuwstadt, 1986). Then z is no longer a primary scaling variable, nor is the boundary-layer depth. The eddies are vertically constrained by strong stratification. However, the z-less concept implies more than small eddies, since vertically continuous turbulence can still organize according to z even if the eddies at any level are small compared to z. For example, with local similarity where the relevant Obukhov length must be recast in terms of local fluxes at level z instead of surface fluxes (Nieuwstadt, 1984), the overall vertical structure is still posed in terms of z/h even if the eddy size is small compared to z. In this sense, local similarity still satisfies the criteria for traditional boundary layers. On the other hand, continuous turbulence between the surface and level z might still qualify as primarily z-less turbulence if the principal source of turbulence is detached from the surface and the distance above the ground surface is only a secondary influence.