• Ballentine, R. J., A. J. Stamm, E. E. Chermack, G. P. Byrd, and D. Schleede, 1998: Mesoscale model simulation of the 4–5 January 1995 lake-effect snowstorm. Wea. Forecasting,13, 893–920.

  • Cao, Z., and H.-R. Cho, 1995: Generation of moist potential vorticity in extratropical cyclones. J. Atmos. Sci.,52, 3263–3281.

  • Chen, S. S., and W. M. Frank, 1993: A numerical study of the genesis of extratropical convective mesovortices. Part I: Evolution and dynamics. J. Atmos. Sci.,50, 2401–2426.

  • Colle, B. A., and C. F. Mass, 1998: Windstorms along the western side of the Washington Cascade Mountains. Part II: Characteristics of past events and three-dimensional idealized simulations. Mon. Wea. Rev.,126, 53–71.

  • Dudhia, J., 1993: A nonhydrostatic version of the Penn State–NCAR Mesoscale Model: Validation tests and simulation of an Atlantic cyclone and cold front. Mon. Wea. Rev.,121, 1493–1513.

  • Fritch, J. M., E. L. Magaziner, and C. F. Chappell, 1980: Analytical initialization for three-dimensional models. J. Appl. Meteor.,19, 809–818.

  • Grell, G. A., J. Dudhia, and D. R. Stauffer, 1994: A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5). NCAR Tech. Note NCAR/TN- 398+STR, 23 pp.

  • Haltiner, G. J., and R. T. Williams, 1980: Numerical Prediction and Dynamic Meteorology. 2d ed. John Wiley and Sons, 477 pp.

  • Holton, J. R., 1995: An Introduction to Dynamic Meteorology. 3d ed. Academic Press, 511 pp.

  • Nuss, W. A., and R. A. Anthes, 1987: A numerical investigation of low-level processes in rapid cyclogenesis. Mon. Wea. Rev.,115, 2728–2743.

  • Shapiro, M. A., and D. Keyser, 1990: Fronts, jet streams and the tropopause. Extratropical Cyclones: The Erik Palmén Memorial Volume, C. Newton and E. O. Holopainen, Eds., Amer. Meteor. Soc., 167–191.

  • Sousounis, P. J., and J. M. Fritsch, 1994: Lake aggregate mesoscale disturbances. Part II: A case study of the effects on regional and synoptic scale weather systems. Bull. Amer. Meteor. Soc.,75, 1793–1812.

  • Stauffer, D. R., N. L. Seaman, T. T. Warner, and A. M. Lario, 1993:Application of an atmospheric simulation model to diagnose air pollution transport in the Grand Canyon region of Arizona. Chem. Eng. Commun.,121, 9–26.

  • Sun, W. Y., and J.-D. Chern, 1994: Numerical experiments of vortices in the wakes of large idealized mountains. J. Atmos. Sci.,51, 191–209.

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A Technique for Generating Idealized Initial and Boundary Conditions for the PSU–NCAR Model MM5

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  • 1 Atmospheric, Oceanic, and Space Sciences Department, The University of Michigan, Ann Arbor, Michigan
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Abstract

A new idealized initialization technique has been developed for the Mesoscale Model version 5 modeling system. The technique allows the specification of baroclinic disturbances that feature vertical variations of the height, temperature, and wind fields in terms of phase lag, wavelength, and phase speed. The technique involves specifying a sounding profile at some reference point, generating the desired height fields using an analytic formulation, constructing the wind fields to be in geostrophic balance, and generating temperature fields using the hydrostatic relationship.

A distinct advantage of this technique over existing ones is that the boundary conditions are not restricted to being specified as periodic. The flexibility means that 1) users do not have to specify a domain whose size is equal to an integer number of wavelengths of the specified flow; 2) users can specify a flow that consists of different wavelengths at different heights, as is typically observed; and 3) any responses that are generated orographically or thermally in the domain and which leave the eastern boundary will not reenter the western boundary. This last item is particularly advantageous because it allows users to study the effects of a preconditioned environment on subsequent development of a featured disturbance rather than studying the repetitive effects of the same forcing mechanism on the same disturbance.

Examples of simulations using initial conditions that are generated with this technique are shown for 1) zonal flow and 2) continuous sinusoidal waves. Flat terrain was adopted for both examples. In example 1, the boundary layer parameterization scheme and surface fluxes were turned off for a simplified zonal flow situation to demonstrate the stability of this technique. During the simulations, the flow remained zonal, exactly as specified, even after 48 h. In example 2, a situation consisting of continuous sinusoidal waves moving across an array of four warm circular lakes was created to demonstrate the utility of the technique for examining how disturbances may be affected by the Great Lakes. Realistic-looking highs, lows, and fronts, along with individual and lake-aggregate enhancements developed by 48 h. Good stability and lack of distortion throughout the domain in both examples add credibility to the technique.

Corresponding author address: Dr. Peter J. Sousounis, Atmospheric, Oceanic, and Space Sciences Department, The University of Michigan, Ann Arbor, MI 48109-2143.

Email: sousou@umich.edu

Abstract

A new idealized initialization technique has been developed for the Mesoscale Model version 5 modeling system. The technique allows the specification of baroclinic disturbances that feature vertical variations of the height, temperature, and wind fields in terms of phase lag, wavelength, and phase speed. The technique involves specifying a sounding profile at some reference point, generating the desired height fields using an analytic formulation, constructing the wind fields to be in geostrophic balance, and generating temperature fields using the hydrostatic relationship.

A distinct advantage of this technique over existing ones is that the boundary conditions are not restricted to being specified as periodic. The flexibility means that 1) users do not have to specify a domain whose size is equal to an integer number of wavelengths of the specified flow; 2) users can specify a flow that consists of different wavelengths at different heights, as is typically observed; and 3) any responses that are generated orographically or thermally in the domain and which leave the eastern boundary will not reenter the western boundary. This last item is particularly advantageous because it allows users to study the effects of a preconditioned environment on subsequent development of a featured disturbance rather than studying the repetitive effects of the same forcing mechanism on the same disturbance.

Examples of simulations using initial conditions that are generated with this technique are shown for 1) zonal flow and 2) continuous sinusoidal waves. Flat terrain was adopted for both examples. In example 1, the boundary layer parameterization scheme and surface fluxes were turned off for a simplified zonal flow situation to demonstrate the stability of this technique. During the simulations, the flow remained zonal, exactly as specified, even after 48 h. In example 2, a situation consisting of continuous sinusoidal waves moving across an array of four warm circular lakes was created to demonstrate the utility of the technique for examining how disturbances may be affected by the Great Lakes. Realistic-looking highs, lows, and fronts, along with individual and lake-aggregate enhancements developed by 48 h. Good stability and lack of distortion throughout the domain in both examples add credibility to the technique.

Corresponding author address: Dr. Peter J. Sousounis, Atmospheric, Oceanic, and Space Sciences Department, The University of Michigan, Ann Arbor, MI 48109-2143.

Email: sousou@umich.edu

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