• Alexander, M. J., J. Holton, and D. Durran, 1995: The gravity wave response above deep convection in a squall line simulation. J. Atmos. Sci., 52 , 22122226.

    • Search Google Scholar
    • Export Citation
  • Asencio, N., J. Stein, M. Chong, and F. Gheusi, 2003: Analysis and simulation of local and regional conditions for the rainfall over the Lago Maggiore target area during MAP IOP2b. Quart. J. Roy. Meteor. Soc., 129 , 565586.

    • Search Google Scholar
    • Export Citation
  • Bougeault, P., and Coauthors, 2001: The MAP special observing period. Bull. Amer. Meteor. Soc., 82 , 433462.

  • Dunkerton, T. J., 1993: Inertial instability of nonparallel flow on an equatorial beta-plane. J. Atmos. Sci., 50 , 27442758.

  • Durran, D. R., and J. B. Klemp, 1982: On the effects of moisture on the Brunt-Väisälä frequency. J. Atmos. Sci., 39 , 21522158.

  • Eckel, F. A., and C. F. Mass, 2005: Aspects of effective mesoscale, short-range ensemble forecasting. Wea. Forecasting, 20 , 328350.

  • Ehrendorfer, M., 1997: Predicting the uncertainty of numerical weather forecasts: A review. Meteor. Z., 6 , 147183.

  • Frei, C., and C. Schär, 1998: A precipitation climatology of the Alps from high-resolution rain-gauge observations. Int. J. Climatol., 18 , 873900.

    • Search Google Scholar
    • Export Citation
  • Frei, C., and E. Häller, 2001: Mesoscale precipitation analysis from MAP SOP rain-gauge data. MAP Newsletter 15, MeteoSwiss, Zürich, Switzerland, 257–260.

  • Fuhrer, O., and C. Schär, 2005: Embedded cellular convection in moist flow past topography. J. Atmos. Sci., 62 , 28102828.

  • Holton, J. R., 2004: An Introduction to Dynamic Meteorology. 4th ed. Academic Press, 535 pp.

  • Huerre, P., and P. Monkewitz, 1985: Absolute and convective instabilities in free shear layers. J. Fluid Mech., 159 , 151168.

  • Jacobsen, I., and E. Heise, 1982: A new economic method for the computation of the surface temperature in numerical models. Contrib. Atmos. Phys., 55 , 128141.

    • Search Google Scholar
    • Export Citation
  • Kessler, E., 1969: On the Distribution and Continuity of Water Substance in Atmospheric Circulation Models. Meteor. Monogr., No. 10, Amer. Meteor. Soc., 84 pp.

  • Klemp, J., and R. Wilhelmson, 1978: Simulation of 3-dimensional convective storm dynamics. J. Atmos. Sci., 35 , 10701096.

  • Lascaux, F., E. Richard, C. Keil, and O. Bock, 2004: Impact of the MAP reanalysis on the numerical simulation of the MAP-IOP2a convective system. Meteor. Z., 13 , 4954.

    • Search Google Scholar
    • Export Citation
  • Lin, S. J., and R. T. Pierrehumbert, 1993: Is the midlatitude zonal flow absolutely unstable? J. Atmos. Sci., 50 , 505517.

  • Lorenz, E. N., 1963: Deterministic nonperiodic flow. J. Atmos. Sci., 20 , 130141.

  • Louis, J., 1979: Parametric model of vertical eddy fluxes in the atmosphere. Bound.-Layer Meteor., 17 , 187202.

  • Marsigli, C., A. Montani, F. Nerozzi, T. Paccagnella, S. Tibaldi, F. Molteni, and R. Buizza, 2001: A strategy for high-resolution ensemble prediction. II: Limited-area experiments in four alpine flood events. Quart. J. Roy. Meteor. Soc., 127 , 20952115.

    • Search Google Scholar
    • Export Citation
  • Marsigli, C., F. Boccanera, A. Montani, and T. Paccagnella, 2005: The COSMO-LEPS mesoscale ensemble system: Validation of the methodology and verification. Nonlinear Processes Geophys., 12 , 527536.

    • Search Google Scholar
    • Export Citation
  • Medina, S., and R. A. Houze, 2003: Air motions and precipitation growth in Alpine storms. Quart. J. Roy. Meteor. Soc., 129 , 345371.

  • Molteni, F., and T. Palmer, 1993: Predictability and finite-time instability of the northern winter circulation. Quart. J. Roy. Meteor. Soc., 119 , 269298.

    • Search Google Scholar
    • Export Citation
  • Molteni, F., R. Buizza, C. Marsigli, A. Montani, F. Nerozzi, and T. Paccagnella, 2001: A strategy for high-resolution ensemble prediction. I: Definition of representative members and global-model experiments. Quart. J. Roy. Meteor. Soc., 127 , 20692094.

    • Search Google Scholar
    • Export Citation
  • Müller, E., 1981: Turbulent flux parameterizations in a regional model. Proc.ECMWF Workshop, Reading, United Kingdom, ECMWF, 193–220.

  • Palmer, T., 2000: Predicting uncertainty in forecasts of weather and climate. Rep. Prog. Phys., 63 , 71116.

  • Richard, E., S. Cosma, P. Tabary, J. P. Pinty, and M. Hagen, 2003: High-resolution numerical simulations of the convective system observed in the Lago Maggiore area on 17 September 1999 (MAP IOP2a). Quart. J. Roy. Meteor. Soc., 129 , 543563.

    • Search Google Scholar
    • Export Citation
  • Richard, E., and Coauthors, 2005: Quantitative precipitation forecasting in mountainous regions pushed ahead by MAP. Extended Abstracts,28th Int. Conf. on Alpine Meteorology and the Annual Scientific Meeting of the Mesoscale Alpine Programme, Zadar, Croatia, Croatian Meteorological Society, S4.2. [Available online at http://meteo.hr/ICAM2005/proceedings.html.].

  • Ritter, B., and J. Geleyn, 1992: A comprehensive radiation scheme for numerical weather prediction models with potential applications in climate simulations. Mon. Wea. Rev., 120 , 303325.

    • Search Google Scholar
    • Export Citation
  • Schär, C., and R. B. Smith, 1993: Shallow-water flow past isolated topography. Part II: Transition to vortex shedding. J. Atmos. Sci., 50 , 14011412.

    • Search Google Scholar
    • Export Citation
  • Skamarock, W., 2004: Evaluating mesoscale NWP models using kinetic energy spectra. Mon. Wea. Rev., 132 , 30193032.

  • Skamarock, W., and J. Klemp, 1992: The stability of time-split numerical-methods for the hydrostatic and the nonhydrostatic elastic equations. Mon. Wea. Rev., 120 , 21092127.

    • Search Google Scholar
    • Export Citation
  • Steppeler, J., G. Doms, U. Schättler, H. Bitzer, A. Gassmann, U. Damrath, and G. Gregoric, 2003: Meso-gamma scale forecasts using the nonhydrostatic model LM. Meteor. Atmos. Phys., 82 , 7596.

    • Search Google Scholar
    • Export Citation
  • Tan, Z., F. Zhang, R. Rotunno, and C. Snyder, 2004: Mesoscale predictability of moist baroclinic waves: Experiments with parameterized convection. J. Atmos. Sci., 61 , 17941804.

    • Search Google Scholar
    • Export Citation
  • Tiedtke, M., 1989: A comprehensive mass flux scheme for cumulus parameterization in large-scale models. Mon. Wea. Rev., 117 , 17791800.

    • Search Google Scholar
    • Export Citation
  • Walser, A., and C. Schär, 2004: Convection-resolving precipitation forecasting and its predictability in Alpine river catchments. J. Hydrol., 288 , 5773.

    • Search Google Scholar
    • Export Citation
  • Walser, A., D. Lüthi, and C. Schär, 2004: Predictability of precipitation in a cloud-resolving model. Mon. Wea. Rev., 132 , 560577.

  • Zhang, F., C. Snyder, and R. Rotunno, 2003: Effects of moist convection on mesoscale predictability. J. Atmos. Sci., 60 , 11731185.

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Predictability Mysteries in Cloud-Resolving Models

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  • 1 Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Switzerland
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Abstract

The rapid amplification of small-amplitude perturbations by the chaotic nature of the atmospheric dynamics intrinsically limits the skill of deterministic weather forecasts. In this study, limited-area cloud-resolving numerical weather prediction (NWP) experiments are conducted to investigate the role of mesoscale processes in determining predictability. The focus is set on domain-internal error growth by integrating an ensemble of simulations using slightly modified initial conditions but identical lateral boundary conditions. It is found that the predictability of the three investigated cases taken from the Mesoscale Alpine Programme (MAP) differs tremendously. In terms of normalized precipitation spread, values between 0.05 (highly predictable) and 1 (virtually unpredictable) are obtained. Analysis of the derived ensemble spread demonstrates that the diabatic forcing associated with moist dynamics is the prime source of rapid error growth. However, in agreement with an earlier study it is found that the differentiation between convective and stratiform rain is unable to account for the distinctive precipitation spreads of the three cases. In particular, instability indices are demonstrated to be poor predictors of the predictability level. An alternate hypothesis is proposed and tested. It is inspired by the dynamical instability theory and states that significant loss of predictability only occurs over moist convectively unstable regions that are able to sustain propagation of energy against the mean flow. Using a linear analysis of gravity wave propagation, this hypothesis is shown to provide successful estimates of the predictability level for the three cases under consideration.

Corresponding author address: Cathy Hohenegger, Institute for Atmospheric and Climate Science, ETH Zürich, Universitätsstr. 16, 8092 Zürich, Switzerland. Email: cathy.hohenegger@env.ethz.ch

Abstract

The rapid amplification of small-amplitude perturbations by the chaotic nature of the atmospheric dynamics intrinsically limits the skill of deterministic weather forecasts. In this study, limited-area cloud-resolving numerical weather prediction (NWP) experiments are conducted to investigate the role of mesoscale processes in determining predictability. The focus is set on domain-internal error growth by integrating an ensemble of simulations using slightly modified initial conditions but identical lateral boundary conditions. It is found that the predictability of the three investigated cases taken from the Mesoscale Alpine Programme (MAP) differs tremendously. In terms of normalized precipitation spread, values between 0.05 (highly predictable) and 1 (virtually unpredictable) are obtained. Analysis of the derived ensemble spread demonstrates that the diabatic forcing associated with moist dynamics is the prime source of rapid error growth. However, in agreement with an earlier study it is found that the differentiation between convective and stratiform rain is unable to account for the distinctive precipitation spreads of the three cases. In particular, instability indices are demonstrated to be poor predictors of the predictability level. An alternate hypothesis is proposed and tested. It is inspired by the dynamical instability theory and states that significant loss of predictability only occurs over moist convectively unstable regions that are able to sustain propagation of energy against the mean flow. Using a linear analysis of gravity wave propagation, this hypothesis is shown to provide successful estimates of the predictability level for the three cases under consideration.

Corresponding author address: Cathy Hohenegger, Institute for Atmospheric and Climate Science, ETH Zürich, Universitätsstr. 16, 8092 Zürich, Switzerland. Email: cathy.hohenegger@env.ethz.ch

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