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Amauri Pereira de Oliveira

Summer School Rio de Janeiro March 2009 2. PBL PROPERTIES. Amauri Pereira de Oliveira. Group of Micrometeorology. Topics. Micrometeorology PBL properties PBL modeling Modeling surface-biosphere interaction Modeling Maritime PBL Modeling Convective PBL. PBL PROPERTIES.

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Amauri Pereira de Oliveira

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  1. Summer SchoolRio de JaneiroMarch 20092. PBL PROPERTIES Amauri Pereira de Oliveira Group of Micrometeorology

  2. Topics • Micrometeorology • PBL properties • PBL modeling • Modeling surface-biosphere interaction • Modeling Maritime PBL • Modeling Convective PBL

  3. PBL PROPERTIES

  4. Turbulent Boundary Layer (TBL) Fluid is moving with velocity U U TBL Rigid Surface Monin. A.S. and Yaglom, A.M., 1971: Statistical Fluid Mechanics, Vol. 1, Massachussets: MIT Press, 769 pp.

  5. Turbulent Boundary Layer Scales characteristics: δ = vertical extension CLT; ν/u* = length scale; ν = kinematics viscosity of fluid (νar 1.5 m2/s); u* = velocity scale; hi = characteristic length scale for the roughness elements of the surface. Monin and Yaglom, 1971.

  6. Internal and external TBL • The TBL can be divided to layers using as a criteria the source of turbulence • Internal layer (“inner-region”): • Shear is intense and most of the turbulence is produced; • Characteristic length scale is ν/u* ; • External layer (“outer-region”): • Shear is small and production of turbulence is also small; • Characteristic length scale is δ. Raupach, M.R., Antonia, R.A. and Rajagopalan, S., 1991: Rough-wall turbulent boundary layers, Applied Mechanics Reviews, 44, 1-25.

  7. Rough and smooth surfaces A surface is aerodynamically smooth when the vertical extension of roughness elements (hi) are smaller than ν/u*. In this case there is a layer adjacent to the surface where the vertical profile of mean velocity varies linearly with height. It is frequently called viscous sub layer. The region of turbulence production is located in the viscous sub layer (internal or inner layer).

  8. Canonical TBL – Smooth surface • Surface rigid and plane; • Horizontal pressure gradient null; • No thermal stratification (Neutral flow) • Aerodynamically smooth surface • Stationary flow

  9. Canonic TBL Logarithmic profile Linear profile Monin. and Yaglom (1971).

  10. TBL – Rough surfaces Raupach et al., 1991.

  11. Planetary Boundary Layer Planetary Boundary Layer (PBL) is the region - adjacent to the surface - where turbulence promotes mixing and most of the exchange of energy, mass and momentum between the surface and atmosphere.

  12. PBL localization Turbulent layer

  13. Diurnal evolution Adapted from Stull (1988).

  14. Homogeneous and plane surfaces Jatos de baixos níveis Sem memória Fernando, H.J.S., Lee, S.M., Anderson, J., Princevac, M., Pardyjak, E. and Grossman-Clarke, S., 2001: Urban fluid mechanics: air circulation and contaminant dispersion in cities. Environmental Fluid Mechanics,1, 107-164.

  15. Convective PBL Nieuwstadt, F.T.M. and Duynkerke, P.G., 1996: Turbulence in the boundary layer, Atmospheric Research, 40, 111-142.

  16. Similarity Theory - CBL Mixing Layer Similarity Monin and Obukhov similarity Free Convection Similarity Nieuwstadt and Duynkerke, 1996.

  17. Monin-Obukhov Similarity Characteristic length scale Obukhov length scale Nieuwstadt and Duynkerke, 1996.

  18. Mixing Layer Similarity Nieuwstadt and Duynkerke, 1996.

  19. Stable Boundary Layer - SBL Nieuwstadt and Duynkerke, 1996.

  20. Similarity theory for SBL Nieuwstadt and Duynkerke, 1996.

  21. Local Similarity Characteristic length scale Local Obukhov length scale. Nieuwstadt and Duynkerke, 1996.

  22. Vertical structure of SBL Nieuwstadt and Duynkerke, 1996.

  23. PBL over heterogeneous surface Urban Boundary Layer Source: Fernando et al. (2001).

  24. BPL – ComplexTopography Source: Hunt et al., 2003 Advection makes turbulence not local.

  25. Surface covered by vegetation • Internal layer: • Inertial layer; • Roughness layer; • Canopy layer; • Canopy sub-layer. Mahrt, L., 2000: Surface heterogeneity and vertical structure of the boundary layer. Boundary-Layer Meteorology, 96: 33-62.

  26. Canopy layer turbulent fluxes Finnigan, J., 2000: Turbulence in plant canopies. Annu. Rev. Fluid Mech., 32, 519–571.

  27. PBL over the ocean • Inertial layer; • Roughness layer. Sjöblom, A. and Smedam, A.-S., 2003: Vertical structure in the marine atmospheric boundary layer and its implication for the inertial dissipation method, Boundary-Layer Meteorology, 109, 1-25 .

  28. Urban Boundary Layer • Internal region: • Inertial; • Roughness layer; • Canopy layer; • Canopy sub-layer. Fonte: Fernando et al. (2001).

  29. UBL structure Fernando et al., 2001.

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