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Parameterization of atmospheric stratification and issues in connection with canopy flow

Parameterization of atmospheric stratification and issues in connection with canopy flow. Sogachev Andrey. Wind Energy Division, Risø National Laboratory for Sustainable Energy , DTU, Building 118, Box 49, DK-4000, Roskilde, Denmark, anso@risoe.dtu.dk .

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Parameterization of atmospheric stratification and issues in connection with canopy flow

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  1. Parameterization of atmospheric stratification and issues in connection with canopy flow Sogachev Andrey Wind Energy Division, Risø National Laboratory for Sustainable Energy, DTU, Building 118, Box 49, DK-4000, Roskilde, Denmark, anso@risoe.dtu.dk

  2. SCADIS(scalar distribution) model:overview • Basic equations: • momentum, • heat, • moisture, • scalars (CO2, SO2, O3), • turbulent kinetic energy (E) • One-and-a-half-order turbulence closure • based on equations of E and ε (dissipation rate) : ( E-l, E-ε.) • E-ω closure based on ω (ε/E) equation • Terrain-following coordinate system • Horizontal and vertical resolutions • (depending on a specific problem) (Sogachev et al., 2002, 2004; Sogachev and Panferov, 2006; Sogachev et al., 2008, Sogachev 2009)

  3. Upper boundary conditions V(t), Q ( t), T(t), q(t), C(t), U(t) 0 3 - 5 km ) Clouds ( t 1 - 10 km T q F V = 0 U = 0 ( ( soil ), soil ), ( soil ), , CO2 l o w e r b o u n d a r y c o n d i t i o n s SCADISmodel: domain (Sogachev et al., 2002, 2004; Sogachev and Panferov, 2006; Sogachev et al., 2008, Sogachev 2009)

  4. 10 - 100 m advection F E R H CO2 ¶ ¶ f f , ¶ ¶ x y G SCADISmodel: physical processes in the model grid-cell (Sogachev et al., 2002, 2004; Sogachev and Panferov, 2006; Sogachev et al., 2008, Sogachev 2009)

  5. Turbulence model: governing equations with with

  6. Accounting for plant drag and buoyancy: the traditional way ? ( Raupach and Shaw, 1982 ) ( Apsley and Castro, 1997) (Blackadar, 1962)

  7. Modelling of Askervein flow Askervein Hill topographic map (brawn isolines) and dimensionless speed-up, ΔS estimated by SCADIS at z = 10 m above the ground (colored field). Figure 1 also shows the reference site (RS) (with ΔS = 0 ), the 210o wind direction in our simulations and the lines A, AA and B along which the measurements were made. Background of Figure 1 is taken from Castro et al., 2003.

  8. Modelling of Askervein flow (b) (a) Dimensionless speed-up, ΔS at z = 10 m above the ground along lines A (a) and AA (b). During measurements along line AA two different sets of instruments were used.

  9. Uncertainties: buoyancy (Baumert and Peters, 2000)

  10. Uncertainties: dissipation ( Ayotte et al., 1999 ) (Sogachev and Panferov., 2006)

  11. Accounting for plant drag and buoyancy: the revised way (Seginer et al., 1976) ( Raupach and Shaw, 1982 ) (Blackadar, 1962) ( Apsley and Castro, 1997) (Sogachev and Panferov, 2006 ) (Sogachev 2009 )

  12. Accounting for plant drag and buoyancy: the revised way

  13. Treatment of the plant drag ►The Elora corn canopy (Wilson et al., 1982; Wilson, 1988) ▲The Pine forest canopy (Katul and Chang, 1999) ◄Furry hill wind-tunnel experiment (Finnigan and Brunet, 1995) (after Sogachev and Panferov, 2006)

  14. Treatment of the plant drag The basic requirement of K-theory – that the length scale of the mixing process be substantially smaller than that of the inhomogeneity in the mean scalar or momentum gradient (Corrsin 1974) – is not violated for disturbed flow and for slow spatial variation of cdA (Finnigan and Belcher, 2004). SCADIS reproduces the experimental variation in length scales (Sogachev and Panferov, 2006)

  15. Verification: low-roughness surface Wind speed ( m s-1 ) Fig. 1 (a) ABL wind evolution and (b) surface characteristics: u* and Monin-Obukhov length, L, during fair weather over low-roughness land derived by E-ω model. Converse Prandtl number (Businger et al. 1971, Sogachev et al. 2002)

  16. Uncertainties: Turbulent Prandtl number, Pr versus Ri

  17. Verification: low-roughness surface Fig. 2 (a) Wind evolutions and (b) wind profiles for different hours in the atmospheric surface layer during fair weather over low-roughness land derived by E-ω and analytical models. (Paulson, 1970)

  18. Verification: forested surface (Laakso et al., 2007)

  19. Uncertainties: buoyancy inside canopy

  20. Uncertainties: buoyancy inside canopy (Sogachev and Panferov, 2006 ) ?

  21. Uncertainties: buoyancy inside canopy

  22. Uncertainties: buoyancy inside canopy H =16 m, LAI = 1.38 (Christen and Novak, 2008)

  23. ABL evolution

  24. Energy budget above canopy layer

  25. Ri in ABL

  26. Low-level jet

  27. Low-level jet effects on wind energy related variables

  28. Summary Much work remains to be done…

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