• Farrell, B. F., 1983: Pulse asymptotics of three-dimensional baroclinic waves. J. Atmos. Sci., 40, 22022210.

  • Farrell, B. F., , and P. J. Ioannou, 1996: Generalized stability theory. Part I: Autonomous operators. J. Atmos. Sci., 53, 20252040.

  • Hakim, G. J., 2005: Vertical structure of midlatitude analysis and forecast errors. Mon. Wea. Rev., 133, 567578.

  • Hakim, G. J., , and A. K. Canavan, 2005: Observed cyclone-anticyclone tropopause vortex asymmetries. J. Atmos. Sci., 62, 231240.

  • Hakim, G. J., , C. Snyder, , and D. J. Muraki, 2002: A new surface model for cyclone-anticyclone asymmetry. J. Atmos. Sci., 59, 24052420.

    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., , and N. V. West, 1979: Baroclinic waves and frontogenesis: Part II: Uniform potential vorticity jet flows—Cold and warm fronts. J. Atmos. Sci., 36, 16631680.

    • Search Google Scholar
    • Export Citation
  • Huerre, P., , and P. A. Monkewitz, 1990: Local and global instabilities in spatially developing flows. Annu. Rev. Fluid Mech., 22, 473537.

    • Search Google Scholar
    • Export Citation
  • Simmons, A. J., , and B. J. Hoskins, 1979: The downstream and upstream development of unstable baroclinic waves. J. Atmos. Sci., 36, 12391254.

    • Search Google Scholar
    • Export Citation
  • Smith, R. B., 1980: Linear theory of stratified hydrostatic flow past an isolated mountain. Tellus, 32, 348364.

  • Snyder, C., , and T. M. Hamill, 2003: Leading Lyapunov vectors of a turbulent baroclinic jet in a quasigeostrophic model. J. Atmos. Sci., 60, 683688.

    • Search Google Scholar
    • Export Citation
  • Stevens, M. R., , and G. J. Hakim, 2005: Perturbation growth in baroclinic waves. J. Atmos. Sci., 62, 28472863.

  • Szunyogh, I., , Z. Toth, , A. V. Zimin, , S. J. Majumdar, , and A. Persson, 2002: Propagation of the effect of targeted observations: The 2000 winter storm reconnaissance program. Mon. Wea. Rev., 130, 11441165.

    • Search Google Scholar
    • Export Citation
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Spatial Growth of Perturbations in a Turbulent Baroclinic Jet

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  • 1 Department of Atmospheric Sciences, University of Washington, Seattle, Washington
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Abstract

The spatial spreading of infinitesimal disturbances superposed on a turbulent baroclinic jet is explored. This configuration is representative of analysis errors in an idealized midlatitude storm track and the insight gained may be helpful to understand the spreading of forecast errors in numerical weather prediction models.

This problem is explored through numerical experiments of a turbulent baroclinic jet that is perturbed with spatially localized disturbances. Solutions from a quasigeostrophic model for the disturbance fields are compared with those for a passive tracer to determine whether disturbances propagate faster than the basic-state flow. Results show that the disturbance spreading rate is sensitive to the structure of the initial disturbance. Disturbances that are localized in potential vorticity (PV) have far-field winds that allow the disturbance to travel downstream faster than disturbances that are initially localized in geopotential, which have no far-field wind. Near the jet, the spread of the disturbance field is observed to exceed the tracer field for PV-localized disturbances, but not for the geopotential-localized disturbances. Spreading rates faster than the flow for geopotential-localized disturbances are found to occur only for disturbances located off the jet axis.

These results are compared with those for zonal and time-independent jets to qualitatively assess the effects of transience and nonlinearity. This comparison suggests that the average properties of localized perturbations to the turbulent jet can be decomposed into a superposition of dynamics associated with a time-independent parallel flow plus a “diffusion” process.

Corresponding author address: Rahul Mahajan, Department of Atmospheric Sciences, University of Washington, Box 351640, Seattle, WA 98195-1640. E-mail: rahulm@atmos.uw.edu

Abstract

The spatial spreading of infinitesimal disturbances superposed on a turbulent baroclinic jet is explored. This configuration is representative of analysis errors in an idealized midlatitude storm track and the insight gained may be helpful to understand the spreading of forecast errors in numerical weather prediction models.

This problem is explored through numerical experiments of a turbulent baroclinic jet that is perturbed with spatially localized disturbances. Solutions from a quasigeostrophic model for the disturbance fields are compared with those for a passive tracer to determine whether disturbances propagate faster than the basic-state flow. Results show that the disturbance spreading rate is sensitive to the structure of the initial disturbance. Disturbances that are localized in potential vorticity (PV) have far-field winds that allow the disturbance to travel downstream faster than disturbances that are initially localized in geopotential, which have no far-field wind. Near the jet, the spread of the disturbance field is observed to exceed the tracer field for PV-localized disturbances, but not for the geopotential-localized disturbances. Spreading rates faster than the flow for geopotential-localized disturbances are found to occur only for disturbances located off the jet axis.

These results are compared with those for zonal and time-independent jets to qualitatively assess the effects of transience and nonlinearity. This comparison suggests that the average properties of localized perturbations to the turbulent jet can be decomposed into a superposition of dynamics associated with a time-independent parallel flow plus a “diffusion” process.

Corresponding author address: Rahul Mahajan, Department of Atmospheric Sciences, University of Washington, Box 351640, Seattle, WA 98195-1640. E-mail: rahulm@atmos.uw.edu
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