• Armi, L., and R. Williams, 1983: The hydraulics of a stratified fluid flowing through a contraction. J. Fluid Mech., 251 , 355375.

  • Bacmeister, J. T., and M. R. Schoeberl, 1989: Breakdown of vertically propagating two-dimensional gravity waves forced by orography. J. Atmos. Sci., 46 , 21092134.

    • Search Google Scholar
    • Export Citation
  • Baines, P. G., 1979: Observations of stratified flow past three-dimensional barriers. J. Geophys. Res., 84 , 78347838.

  • Bannon, P. R., 1985: Flow acceleration and mountain drag. J. Atmos. Sci., 42 , 24452453.

  • Bannon, P. R., and J. A. Zehnder, 1985: Surface pressure and mountain drag for transient airflow over a mountain ridge. J. Atmos. Sci., 42 , 24542462.

    • Search Google Scholar
    • Export Citation
  • Banta, R. M., L. D. Olivier, W. D. Neff, D. H. Levinson, and D. Ruffieux, 1995: Influence of canyon-induced flows on flow and dispersion over adjacent plains. Theor. Appl. Climatol., 52 , 2742.

    • Search Google Scholar
    • Export Citation
  • Banta, R. M., L. D. Olivier, P. H. Gudiksen, and R. Lange, 1996: Implications of small-scale flow features to modeling dispersion over complex terrain. J. Appl. Meteor., 35 , 330342.

    • Search Google Scholar
    • Export Citation
  • Bleck, R., and S. G. Benjamin, 1993: Regional weather prediction with a model combining terrain-following and isentropic coordinates. Part I: Model description. Mon. Wea. Rev., 121 , 17701785.

    • Search Google Scholar
    • Export Citation
  • Blumen, W., and C. D. McGregor, 1976: Wave drag by three-dimensional mountain lee-waves in nonplanar shear flow. Tellus, 28 , 287298.

  • Bossert, J. E., and G. S. Poulos, 1995: A numerical investigation of mechanisms affecting drainage flows in highly complex terrain. Theor. Appl. Climatol., 52 , 119134.

    • Search Google Scholar
    • Export Citation
  • Brighton, P. W. M., 1978: Strongly stratified flow past three-dimensional obstacles. Quart. J. Roy. Meteor. Soc., 104 , 289307.

  • Buettner, K. J. K., and N. Thyer, 1965: Valley winds in the Mount Ranier area. Arch. Meteor. Geophys. Bioklimatol., 14 , 125147.

  • Chow, F. K., A. P. Weigel, R. L. Street, M. W. Rotach, and M. Xue, 2006: High-resolution large-eddy simulations of flow in a steep Alpine valley. Part I: Methodology, verification, and sensitivity experiments. J. Appl. Meteor., 45 , 6386.

    • Search Google Scholar
    • Export Citation
  • Clark, T. L., 1977: A small-scale dynamic model using a terrain-following coordinate transformation. J. Comput. Phys., 24 , 186215.

  • Clark, T. L., and W. R. Peltier, 1984: Critical level reflection and resonant growth of nonlinear mountain waves. J. Atmos. Sci., 41 , 31213134.

    • Search Google Scholar
    • Export Citation
  • Coulter, R. L., and P. Gudiksen, 1995: The dependence of canyon winds and surface cooling and external forcing in Colorado’s Front Range. J. Appl. Meteor., 34 , 14191429.

    • Search Google Scholar
    • Export Citation
  • Derbyshire, S. H., 1999: Boundary-layer decoupling over cold surfaces as a physical boundary instability. Bound.-Layer Meteor., 90 , 297325.

    • Search Google Scholar
    • Export Citation
  • Durran, D. R., 1986: Another look at downslope windstorms. Part I: The development of analogs to supercritical flow in and infinitely deep, continuously stratified fluid. J. Atmos. Sci., 43 , 25272543.

    • Search Google Scholar
    • Export Citation
  • Durran, D. R., 1990: Mountain waves and downslope winds. Atmospheric Processes in Complex Terrain, Meteor. Monogr., No. 45, Amer. Meteor. Soc., 59–81.

  • Fujita, T. T., 1986: Mesoscale classifications: Their history and their application to forecasting. Mesoscale Meteorology and Forecasting, P. S. Ray, Ed., Amer. Meteor. Soc., 18–35.

    • Search Google Scholar
    • Export Citation
  • Jackson, P. L., and D. G. Steyn, 1994: Gap winds in a fjord. Part II: Hydraulic analog. Mon. Wea. Rev., 122 , 26662676.

  • Klemp, J. B., and R. B. Wilhelmson, 1978: The simulation of three-dimensional convective storm dynamics. J. Atmos. Sci., 35 , 10701096.

    • Search Google Scholar
    • Export Citation
  • Lee, J. T., R. E. Lawson Jr., and G. L. Marsh, 1987: Flow visualization experiments on stably stratified flow over ridges and valleys. Meteor. Atmos. Phys., 37 , 183194.

    • Search Google Scholar
    • Export Citation
  • Lee, T. J., R. A. Pielke, R. C. Kessler, and J. Weaver, 1989: Influence of cold pools downstream of mountain barriers on downslope winds and flushing. Mon. Wea. Rev., 117 , 20412058.

    • Search Google Scholar
    • Export Citation
  • Lester, P. F., and W. A. Fingerhut, 1974: Lower turbulent zones associated with mountain lee waves. J. Appl. Meteor., 13 , 5461.

  • Mahrt, L., 1982: Momentum balance of gravity flows. J. Atmos. Sci., 39 , 27012711.

  • Mahrt, L., 1998: Stratified atmospheric boundary layers and breakdown of models. J. Theor. Comput. Fluid Dyn., 11 , 263280.

  • McKee, T. B., and R. D. O’Neal, 1989: The role of valley geometry and energy budget in the formation of nocturnal valley winds. J. Appl. Meteor., 28 , 445456.

    • Search Google Scholar
    • Export Citation
  • Olafsson, H., and P. Bougeault, 1996: Nonlinear flow past and elliptic mountain ridge. J. Atmos. Sci., 53 , 24652489.

  • Pan, F., and R. B. Smith, 1999: Gap winds and wakes: SAR observation and numerical simulations. J. Atmos. Sci., 56 , 905923.

  • Pan, Z., S. G. Benjamin, J. M. Brown, and T. Smirnova, 1994: Comparative experiments with MAPS on different parameterization schemes for surface moisture flux and boundary-layer processes. Mon. Wea. Rev., 122 , 449470.

    • Search Google Scholar
    • Export Citation
  • Pielke, R. A., 1984: Mesoscale Meteorological Modeling. Academic Press, 612 pp.

  • Pielke, R. A., and Coauthors, 1992: A comprehensive meteorological modeling system—RAMS. Meteor. Atmos. Phys., 49 , 6991.

  • Poulos, G. S., 1996: The interaction of katabatic winds and mountain waves. Ph.D. dissertation, Colorado State University, 297 pp. [Los Alamos National Laboratory Publication LA-13224-T, Los Alamos, New Mexico.].

  • Poulos, G. S., and J. E. Bossert, 1995: An observational and prognostic numerical investigation of complex terrain dispersion. J. Appl. Meteor., 34 , 650669.

    • Search Google Scholar
    • Export Citation
  • Poulos, G. S., and S. P. Burns, 2003: An evaluation of bulk Ri-based surface layer flux formulas for stable and very stable condition with intermittent turbulence. J. Atmos. Sci., 60 , 25232537.

    • Search Google Scholar
    • Export Citation
  • Poulos, G. S., J. E. Bossert, T. B. McKee, and R. A. Pielke, 2000: The interaction of katabatic flow and mountain waves. Part I: Observations and idealized simulations. J. Atmos. Sci., 57 , 19191936.

    • Search Google Scholar
    • Export Citation
  • Queney, P., 1948: The problem of airflow over mountains: A summary of theoretical studies. Bull. Amer. Meteor. Soc., 29 , 1626.

  • Queney, P., G. A. Corby, N. Gerbier, H. Koschmieder, and J. Zierep, 1960: The airflow over mountains. Tech. Note 34, World Meteorological Organization, 135 pp.

  • Reed, T. R., 1931: Gap winds of the Strait of Juan de Fuca. Mon. Wea. Rev., 59 , 373376.

  • Reisner, J. M., and P. K. Smolarkiewicz, 1994: Thermally forced low Froude number flow past three-dimensional obstacles. J. Atmos. Sci., 51 , 117133.

    • Search Google Scholar
    • Export Citation
  • Saunders, P. M., 1987: Flow through Discovery Gap. J. Phys. Oceanogr., 17 , 631643.

  • Skyllingstad, E. D., 2003: Large-eddy simulation of katabatic flows. Bound.-Layer Meteor., 106 , 217243.

  • Smith, C. M., and E. D. Skyllingstad, 2005: Numerical simulation of katabatic flow with changing slope angle. Mon. Wea. Rev., 133 , 30653080.

    • Search Google Scholar
    • Export Citation
  • Smith, R. B., 1979: The influence of mountains on the atmosphere. Advances in Geophysics, Vol. 21, Academic Press, 87–230.

  • Smith, R. B., 1989: Mountain-induced stagnation points in hydrostatic flow. Tellus, 41A , 270274.

  • Song, J. L., R. A. Pielke, M. Segal, R. W. Arritt, and R. Kessler, 1985: A method to determine nonhydrostatic effects within subdomains within a mesoscale model. J. Atmos. Sci., 42 , 21102120.

    • Search Google Scholar
    • Export Citation
  • Stein, U., and P. Alpert, 1993: Factor separation in numerical simulations. J. Atmos. Sci., 50 , 21072115.

  • Tripoli, G. J., and W. R. Cotton, 1982: The Colorado State University three-dimensional cloud/mesoscale model-1982. Part I: General theoretical framework and sensitivity experiments. J. Rech. Atmos., 16 , 185220.

    • Search Google Scholar
    • Export Citation
  • Viterbo, P., A. Beljaars, J-F. Mahfouf, and J. Teixeira, 1999: The representation of soil moisture freezing and its impact on the stable boundary layer. Quart. J. Roy. Meteor. Soc., 125 , 24012426.

    • Search Google Scholar
    • Export Citation
  • Weigel, A. P., F. K. Chow, M. W. Rotach, R. L. Street, and M. Xue, 2006: High-resolution large-eddy simulations of flow in a steep Alpine valley. Part II: Flow structure and heat budgets. J. Appl. Meteor. Climatol., 45 , 87107.

    • Search Google Scholar
    • Export Citation
  • Weissbluth, M. J., and W. R. Cotton, 1989: Radiative and nonlinear influences on orographic gravity wave drag. Mon. Wea. Rev., 117 , 25182534.

    • Search Google Scholar
    • Export Citation
  • Whiteman, C. D., 1990: Observations of thermally developed wind systems in mountainous terrain. Atmospheric Processes over Complex Terrain, Meteor. Monogr., No. 45, Amer. Meteor. Soc., 5–42.

  • Zängl, G., 2002: Stratified flow over a mountain with a gap: Linear theory and numerical simulations. Quart. J. Roy. Meteor. Soc., 128 , 927949.

    • Search Google Scholar
    • Export Citation
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The Interaction of Katabatic Flow and Mountain Waves. Part II: Case Study Analysis and Conceptual Model

Gregory S. PoulosNational Center for Atmospheric Research,* Earth Observing Laboratory, Boulder, Colorado

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James E. BossertLos Alamos National Laboratory, Los Alamos, New Mexico

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Thomas B. McKeeColorado State University, Fort Collins, Colorado

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Roger A. Pielke Sr.Colorado State University, Fort Collins, Colorado

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Abstract

Via numerical analysis of detailed simulations of an early September 1993 case night, the authors develop a conceptual model of the interaction of katabatic flow in the nocturnal boundary layer with mountain waves (MKI). A companion paper (Part I) describes the synoptic and mesoscale observations of the case night from the Atmospheric Studies in Complex Terrain (ASCOT) experiment and idealized numerical simulations that manifest components of the conceptual model of MKI presented herein. The reader is also referred to Part I for detailed scientific background and motivation.

The interaction of these phenomena is complicated and nonlinear since the amplitude, wavelength, and vertical structure of the mountain-wave system developed by flow over the barrier owes some portion of its morphology to the evolving atmospheric stability in which the drainage flows develop. Simultaneously, katabatic flows are impacted by the topographically induced gravity wave evolution, which may include significantly changing wavelength, amplitude, flow magnitude, and wave breaking behavior. In addition to effects caused by turbulence (including scouring), perturbations to the leeside gravity wave structure at altitudes physically distant from the surface-based katabatic flow layer can be reflected in the katabatic flow by transmission through the atmospheric column. The simulations show that the evolution of atmospheric structure aloft can create local variability in the surface pressure gradient force governing katabatic flow. Variability is found to occur on two scales, on the meso-β due to evolution of the mountain-wave system on the order of one hour, and on the microscale due to rapid wave evolution (short wavelength) and wave breaking–induced fluctuations. It is proposed that the MKI mechanism explains a portion of the variability in observational records of katabatic flow.

Corresponding author address: Gregory S. Poulos, NCAR-EOL, P.O. Box 3000, Boulder, CO 80307-3000. Email: gsp@ucar.edu

Abstract

Via numerical analysis of detailed simulations of an early September 1993 case night, the authors develop a conceptual model of the interaction of katabatic flow in the nocturnal boundary layer with mountain waves (MKI). A companion paper (Part I) describes the synoptic and mesoscale observations of the case night from the Atmospheric Studies in Complex Terrain (ASCOT) experiment and idealized numerical simulations that manifest components of the conceptual model of MKI presented herein. The reader is also referred to Part I for detailed scientific background and motivation.

The interaction of these phenomena is complicated and nonlinear since the amplitude, wavelength, and vertical structure of the mountain-wave system developed by flow over the barrier owes some portion of its morphology to the evolving atmospheric stability in which the drainage flows develop. Simultaneously, katabatic flows are impacted by the topographically induced gravity wave evolution, which may include significantly changing wavelength, amplitude, flow magnitude, and wave breaking behavior. In addition to effects caused by turbulence (including scouring), perturbations to the leeside gravity wave structure at altitudes physically distant from the surface-based katabatic flow layer can be reflected in the katabatic flow by transmission through the atmospheric column. The simulations show that the evolution of atmospheric structure aloft can create local variability in the surface pressure gradient force governing katabatic flow. Variability is found to occur on two scales, on the meso-β due to evolution of the mountain-wave system on the order of one hour, and on the microscale due to rapid wave evolution (short wavelength) and wave breaking–induced fluctuations. It is proposed that the MKI mechanism explains a portion of the variability in observational records of katabatic flow.

Corresponding author address: Gregory S. Poulos, NCAR-EOL, P.O. Box 3000, Boulder, CO 80307-3000. Email: gsp@ucar.edu

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