Abstract
Large-eddy simulations of the convective boundary layer are compared over hilly versus flat surfaces. Moderate values for the height and horizontal spacing of the hills were selected. Thermally-direct hill-valley circulations are induced by the uneven terrain, accounting for a significant fraction of the resolved energy in the boundary-layer eddies. The probability of upward eddy motion reaches up to 70% over the hilltops and down to 15% over the valleys. Above-average values of both subgrid scale turbulent kinetic energy and upward eddy heat transport are found above the higher terrain. Horizontal spectra of vertical motion are strongly biased toward the horizontal scales of the terrain. Vertical profiles of atmospheric variables obtained by horizontal averaging, however, exhibit no significant differences between hilly and flat terrain simulations.
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Businger, J. A., Wyngaard, J. C., Izumi, Y., and Bradley, E. F.: 1971, ‘Flux-Profile Relationships in the Atmospheric Surface Layer’, J. Atmos. Sci. 28 181–189.
Carras, J. N. and Williams, D. J.: 1981, ‘The Long-Range Dispersion of a Plume from an Isolated Point Source’, Atmos. Environ. 15 2205–2217.
Deardorff, J. W.: 1974: ‘Three-Dimensional Numerical Study of the Height and Mean Structure of a Heated Planetary Boundary Layer’, Boundary-Layer Meteorol. 7 81–106.
Deardorff, J. W.: 1980, ‘Stratocumulus-Capped Mixed Layers Derived from a Three-Dimensional Model’, Boundary-Layer Meteorol. 18 495–527.
Gal-Chen, T. and Somerville, R. C. J.: 1975, ‘On the Use of a Coordinate Transformation for the Solution of the Navier-Stokes Equation’, J. Comp. Physics 17 209–228.
Grant, A. L. M. and Mason, P. J.: 1990, ‘Observations of Boundary-Layer Structure over Complex Terrain’, Quart. J. R. Meteorol. Soc. 11 159–186.
Hadfield, M. G.: 1988, The Response of the Atmospheric Convective Boundary Layer to Surface Inhomogeneities, Colorado State University, Atmospheric Science Paper No. 433, Fort Collins, CO.
Hadfield, M. G., Cotton, W. R., and Pielke, R. A.: 1991a, ‘Lare-Eddy Simulations of a Small-Scale, Thermally-Forced Circulation in the Convective Boundary Layer’, Boundary-Layer Meteorol. 57 79–114.
Hadfield, M. G., Cotton, W. R., and Pielke, R. A.: 1991b, ‘Thermally Forced Circulations in the Convective Boundary Layer — The Effect of Changes in Wavelength and Wind Speed ’, Boundary-Layer Meteorol. (in press)
Han, Y.-J., Ueyoshi, K., and Deardorff, J. W.: 1982: ‘Numerical Study of Terrain-Induced Mesoscale Motions in a Mixed Layer’, J. Atmos. Sci. 39 2464–2476.
Kaimal, J. C., Eversole, R. A., Lenschow, D. H., Stankhov, B. B., Kahn, P. H., and Businger, J. A.: 1982: ‘Spectral Characteristics of the Convective Boundary Layer Over Uneven Terrain’, J. Atmos. Sci. 39 1098–1114.
King, J. C.: 1990, The Atmospheric Boundary Layer over an Antarctic Ice Shelf, Preprint, Ninth Symposium on Turbulence and Diffusion, Amer. Meteor. Soc., Boston, pp. 334–336.
Krettenauer, K. and Schumann, U.: 1989, ‘Direct Numerical Simulation of Thermal Convection over a Wavy Surface’, Meteorol. Atmos. Phys. 41 165–179.
Kustas, W. P. and Brutsaert, W.: 1986, ‘Wind Profile Constants in a Neutral Atmospheric Boundary Layer over Complex Terrain’, Boundary-Layer Meteorol. 34 33–54.
Moeng, C.-H., Wyngaard, J. C.: 1984, ‘Statistics of Conservative Scalars in the Convective Boundary Layer’, J. Atmos. Sci. 41 2052–2062.
Moeng, C.-H., and Wyngaard, J. C.: 1988, ‘Spectral Analysis of Large-Eddy Simulations of the Convective Boundary Layer’, J. Atmos. Sci. 45 3573–3587.
Nieuwstadt, F. T. M. and Glendening, J. W.: 1989, ‘Mesoscale Dynamics of the Depth of a Horizontally Non-Homogeneous, Well-Mixed Boundary Layer’, Beitr. Phys. Atmosph. 62 275–288.
Panofsky, H. A., Larko, D., Lipschutz, R., Stone, G., Bradley, E. F., Bowen, A. J., and Højstrup, J.: 1982, ‘Spectra of Velocity Components over Complex Terrain’, Quart. J. R. Meteorol. Soc. 108 215–230.
Reiter, E. R.: 1969, ‘Mean and Eddy Motions in the Atmosphere’, Mon. Wea. Rev. 97 200–204.
Schmidt, H. and Schumann, U.: 1989, ‘Coherent Structure of the Convective Boundary Layer Derived from Large-Eddy Simulations’, J. Fluid Mech. 200 511–562.
Schumann, U.: 1990, ‘Large-Eddy Simulation of the Up-Slope Boundary Layer’, Quart. J. Roy. Meteorol. Soc. 116 637–670.
Shao, Y. and Hacker, J. M.: 1990, ‘Local Similarity Relationships in a Horizontally Inhomogeneous Boundary Layer’, Boundary-Layer Meteorol. 52 17–40.
Young, G. S.: 1988, ‘‘Turbulence Structure of the Convective Boundary Layer’, Part II: Phoenix 78 Aircraft Observations of Thermals and their Environment’, J. Atmos. Sci. 45 727–735.
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Walko, R.L., Cotton, W.R. & Pielke, R.A. Large-eddy simulations of the effects of hilly terrain on the convective boundary layer. Boundary-Layer Meteorol 58, 133–150 (1992). https://doi.org/10.1007/BF00120755
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DOI: https://doi.org/10.1007/BF00120755