• Alessio, S., , L. Briatore, , R. Cremonini, , E. Ferrero, , C. Giraud, , A. Longhetto, , O. Morra, , and R. Purini, 1995: Laboratory simulations of inertial and frictional effects on barotropic rotating flows over and past obstacles: Comparison with simple numerical and analytical model. Nuovo Cimento, 18C , 603627.

    • Search Google Scholar
    • Export Citation
  • Bannon, P. R., 1980: Rotating barotropic flow over finite isolated topography. J. Fluid Mech., 101 , 281306.

  • Boyer, D. L., , and X. Zhang, 1990: The interaction of time-dependent rotating and stratified flow with isolated topography. Dyn. Atmos. Oceans, 14 , 543575.

    • Search Google Scholar
    • Export Citation
  • Buzzi, A., , and S. Tibaldi, 1977: Inertial and frictional effects on rotating and stratified flow over topography. Quart. J. Roy. Meteor. Soc., 103 , 135150.

    • Search Google Scholar
    • Export Citation
  • Canuto, V. M., , and Y. Cheng, 1997: Determination of the Smagorinsky–Lilly constant Cs. Phys. Fluids, 9 , 13681378.

  • Davies, P. A., 1972: Experiments on Taylor columns in rotating stratified fluids. J. Fluid Mech., 54 , 691717.

  • Hide, R., 1961: Origins of Jupiter's great red spot. Nature, 190 , 895896.

  • Holton, J. R., 1992: An Introduction to Dynamic Meteorology. 3d ed. Academic Press, 511 pp.

  • Huppert, H. E., 1975: Some remarks on the initiation of inertial Taylor columns. J. Fluid Mech., 67 , 397412.

  • Huppert, H. E., , and K. Bryan, 1976: Topographically generated eddies. Deep-Sea Res., 23 , 655679.

  • Jacobs, S. J., 1964: The Taylor column problem. J. Fluid Mech., 20 , 581591.

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

    • Search Google Scholar
    • Export Citation
  • Lilly, D. K., 1966: On the application of the eddy viscosity concept in the inertial subrange of turbulence. NCAR Manuscript 123, NCAR, 19 pp.

    • Search Google Scholar
    • Export Citation
  • Pedlosky, J., 1987: Geophysical Fluid Dynamics. 2d ed. Springer-Verlag 710 pp.

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

  • Schär, C., , and D. R. Durran, 1997: Vortex formation and vortex shedding in continuously stratified flows past isolated topography. J. Atmos. Sci., 54 , 534554.

    • Search Google Scholar
    • Export Citation
  • Sun, W. Y., , and J. D. Chern, 1994: Numerical experiments of vortices in the wakes of large idealized mountains. J. Atmos. Sci., 51 , 191209.

    • Search Google Scholar
    • Export Citation
  • Taylor, G. I., 1923: Experiments on the motion of solid bodies in rotating fluids. Proc. Roy. Soc. London, 93 , 99113.

  • Thompson, L., , and G. R. Flierl, 1993: Barotropic flow over finite isolated topography: Steady solutions on the beta-plane and the initial value problem. J. Fluid Mech., 250 , 553586.

    • Search Google Scholar
    • Export Citation
  • Trini Castelli, S., , E. Ferrero, , and D. Anfossi, 1997: Comparison between different turbulence closures in a flow model applied to a schematic 2-D valley in a wind tunnel experiment. Proc. Second European and African Conf. on Wind Engineering, Genoa, Italy, DISEG, 317–324.

    • Search Google Scholar
    • Export Citation
  • Vaziri, A., , and D. L. Boyer, 1971: Rotating flow over shallow topographies. J. Fluid Mech., 50 , 7995.

  • Zhang, X., , D. S. McGuinness, , and D. L. Boyer, 1994: Narrow barotropic current impinging on an isolated seamount. J. Geophys. Res., 99 , 2270722724.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 109 109 0
PDF Downloads 1 1 0

Numerical Experiments of Barotropic Flow Interaction with a 3D Obstacle

View More View Less
  • 1 Dipartimento di Scienze e Tecnologie Avanzate, Universitá del Piemonte Orientale “A. Avogadro,” Alessandria, Italy
  • | 2 Dipartimento di Fisica Generale, Universitá di Torino, Torino, Italy
© Get Permissions
Restricted access

Abstract

In this paper the results of numerical simulation experiments on the interaction between a neutrally stratified atmospheric flow and a symmetric 3D obstacle are presented and discussed. These experiments provide evidence of the presence of an ageostrophic (AGG) vorticity structure, interacting with the obstacle and hidden beneath the upper cyclone–anticyclone dipole predicted by the quasigeostrophic (QG) theory. The AGG cyclone was disclosed when the numerical simulations were run with velocities of the mean flow exceeding a critical threshold, which allowed the upper QG cyclone to be advected downstream of the obstacle. The numerical circulation model, resolving the primitive flow equations and used in our simulations, was applied to a square domain of 2000 km × 2000 km. A 3000-m-high Gaussian-shaped obstacle, characterized by a half-height width of 400 km, was placed at the center of the domain. This obstacle provided the topographic forcing, which was the source of the disturbances on the flow. The simulations were characterized by different values of the mean-flow Rossby number: an analysis of the relative role played by the different forces involved in such a process permitted the isolation of the main mechanism originating the ageostrophic structure, which was not clearly identified in previous works.

Corresponding author address: Dr. E. Ferrero, Universitá degli Studi del Piemonte Orientale, Dipartimento di Scienze e Tecnologie Avanzate, Corso T. Borsalino 54, Alessandria 15100, Italy. Email: ferrero@unipmn.it

Abstract

In this paper the results of numerical simulation experiments on the interaction between a neutrally stratified atmospheric flow and a symmetric 3D obstacle are presented and discussed. These experiments provide evidence of the presence of an ageostrophic (AGG) vorticity structure, interacting with the obstacle and hidden beneath the upper cyclone–anticyclone dipole predicted by the quasigeostrophic (QG) theory. The AGG cyclone was disclosed when the numerical simulations were run with velocities of the mean flow exceeding a critical threshold, which allowed the upper QG cyclone to be advected downstream of the obstacle. The numerical circulation model, resolving the primitive flow equations and used in our simulations, was applied to a square domain of 2000 km × 2000 km. A 3000-m-high Gaussian-shaped obstacle, characterized by a half-height width of 400 km, was placed at the center of the domain. This obstacle provided the topographic forcing, which was the source of the disturbances on the flow. The simulations were characterized by different values of the mean-flow Rossby number: an analysis of the relative role played by the different forces involved in such a process permitted the isolation of the main mechanism originating the ageostrophic structure, which was not clearly identified in previous works.

Corresponding author address: Dr. E. Ferrero, Universitá degli Studi del Piemonte Orientale, Dipartimento di Scienze e Tecnologie Avanzate, Corso T. Borsalino 54, Alessandria 15100, Italy. Email: ferrero@unipmn.it

Save