Editorial Type:
Article
Article Type:
Research Article

Effects of Horizontal and Vertical Grid Spacing on Mixing in Simulated Squall Lines and Implications for Convective Strength and Structure

Z. J. Lebo Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, and NOAA/Earth System Research Laboratory, Chemical Sciences Division, Boulder, Colorado

Search for other papers by Z. J. Lebo in
Current site
Google Scholar
PubMed Close
and
H. Morrison Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, Boulder, Colorado

Search for other papers by H. Morrison in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Nov 2015
DOI:
https://doi.org/10.1175/MWR-D-15-0154.1
Page(s):
4355–4375
Restricted access

Abstract

The sensitivity of an idealized squall line to horizontal and vertical grid spacing is investigated using a new approach. Simulations are first performed at a horizontal grid spacing of 1 km until the storm reaches its mature stage. The model output is then interpolated to smaller (and larger) grid spacings, and the model is restarted using the interpolated state plus small thermodynamic perturbations to spin up small-scale motions. This framework allows an investigation of the sensitivity of the storm to changes in without complications from differences in storm initiation and early evolution. The restarted simulations reach a quasi steady state within approximately 1 h. Results demonstrate that there are two -dependent regimes with the transition between regimes occurring for between 250 and 500 m. Some storm characteristics, such as the mean convective core area, change substantially for 250 m but show limited sensitivity as is decreased below 250 m, despite better resolving smaller-scale turbulent motions. This transition is found to be independent of the chosen . Mixing in the context of varying and is also investigated via passive tracers that are initialized 1 h after restarting the simulations (i.e., after the spin up of small-scale motions). The tracer field at the end of the simulations reveals that entrainment and detrainment are suppressed in the simulations with 500 m. For decreasing , entrainment and detrainment are substantially more important, limiting the flux of low-level tracer to the upper troposphere, which has important implications for modeling studies of convective transport from the boundary layer through the troposphere.

Current affiliation: Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming.

The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Corresponding author address: Z. J. Lebo, Department of Atmospheric Science, University of Wyoming, 1000 East University Ave., Laramie, WY 82071. E-mail: zlebo@uwyo.edu

Abstract

The sensitivity of an idealized squall line to horizontal and vertical grid spacing is investigated using a new approach. Simulations are first performed at a horizontal grid spacing of 1 km until the storm reaches its mature stage. The model output is then interpolated to smaller (and larger) grid spacings, and the model is restarted using the interpolated state plus small thermodynamic perturbations to spin up small-scale motions. This framework allows an investigation of the sensitivity of the storm to changes in without complications from differences in storm initiation and early evolution. The restarted simulations reach a quasi steady state within approximately 1 h. Results demonstrate that there are two -dependent regimes with the transition between regimes occurring for between 250 and 500 m. Some storm characteristics, such as the mean convective core area, change substantially for 250 m but show limited sensitivity as is decreased below 250 m, despite better resolving smaller-scale turbulent motions. This transition is found to be independent of the chosen . Mixing in the context of varying and is also investigated via passive tracers that are initialized 1 h after restarting the simulations (i.e., after the spin up of small-scale motions). The tracer field at the end of the simulations reveals that entrainment and detrainment are suppressed in the simulations with 500 m. For decreasing , entrainment and detrainment are substantially more important, limiting the flux of low-level tracer to the upper troposphere, which has important implications for modeling studies of convective transport from the boundary layer through the troposphere.

Current affiliation: Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming.

The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Corresponding author address: Z. J. Lebo, Department of Atmospheric Science, University of Wyoming, 1000 East University Ave., Laramie, WY 82071. E-mail: zlebo@uwyo.edu
Save
Cover Monthly Weather Review
Monthly Weather Review

  • Adlerman, E. J., and K. K. Droegemeier, 2002: The sensitivity of numerically simulated cyclic mesocyclogenesis to variations in model physical and computational parameters. Mon. Wea. Rev., 130, 2671–2691, doi:10.1175/1520-0493(2002)130<2671:TSONSC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Belair, S., and J. Mailhot, 2001: Impact of horizontal resolution on the numerical simulation of a midlatitude squall line: Implicit versus explicit condensation. Mon. Wea. Rev., 129, 2362–2376, doi:10.1175/1520-0493(2001)129<2362:IOHROT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Bryan, G. H., and H. Morrison, 2012: Sensitivity of a simulated squall line to horizontal resolution and parameterization of microphysics. Mon. Wea. Rev., 140, 202–225, doi:10.1175/MWR-D-11-00046.1.

    • Search Google Scholar
    • Export Citation

  • Bryan, G. H., J. C. Wyngaard, and J. M. Fritsch, 2003: Resolution requirements for the simulation of deep moist convection. Mon. Wea. Rev., 131, 2394–2416, doi:10.1175/1520-0493(2003)131<2394:RRFTSO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Craig, G. C., and A. Dornbrack, 2008: Entrainment in cumulus clouds: What resolution is cloud-resolving? J. Atmos. Sci., 65, 3978–3988, doi:10.1175/2008JAS2613.1.

    • Search Google Scholar
    • Export Citation

  • Dawson, D. T., II, M. Xue, J. A. Milbrandt, and M. K. Yau, 2010: Comparison of evaporation and cold pool development between single-moment and multimoment bulk microphysics schemes in idealized simulations of tornadic thunderstorms. Mon. Wea. Rev., 138, 1152–1171, doi:10.1175/2009MWR2956.1.

    • Search Google Scholar
    • Export Citation

  • de Rooy, W. C., and A. P. Siebesma, 2008: A simple parameterization for detrainment in shallow cumulus. Mon. Wea. Rev., 136, 560–576, doi:10.1175/2007MWR2201.1.

    • Search Google Scholar
    • Export Citation

  • Done, J., C. A. Davis, and M. Weisman, 2004: The next generation of NWP: Explicit forecasts of convection using the Weather Research and Forecasting (WRF) Model. Atmos. Sci. Lett., 5, 110–117, doi:10.1002/asl.72.

    • Search Google Scholar
    • Export Citation

  • Fiori, E., A. Parodi, and F. Siccardi, 2010: Turbulence closure parameterization and grid spacing effects in simulated supercells. J. Atmos. Sci., 67, 3870–3890, doi:10.1175/2010JAS3359.1.

    • Search Google Scholar
    • Export Citation

  • Fiori, E., A. Parodi, and F. Siccardi, 2011: Uncertainty in prediction of deep moist convection processes: Turbulence parameterizations, microphysics and grid-scale effects. Atmos. Res., 100, 447–456, doi:10.1016/j.atmosres.2010.10.003.

    • Search Google Scholar
    • Export Citation

  • Gentry, M. S., and G. M. Lackmann, 2010: Sensitivity of simulated tropical cyclone structure and intensity to horizontal resolution. Mon. Wea. Rev., 138, 688–704, doi:10.1175/2009MWR2976.1.

    • Search Google Scholar
    • Export Citation

  • Grabowski, W. W., 1998: Toward cloud resolving modeling large-scale tropical circulations: A simple cloud microphysics parameterization. J. Atmos. Sci., 55, 3283–3298, doi:10.1175/1520-0469(1998)055<3283:TCRMOL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Grabowski, W. W., 2001: Coupling cloud processes with the large-scale dynamics using the Cloud-Resolving Convection Parameterization (CRCP). J. Atmos. Sci., 58, 978–997, doi:10.1175/1520-0469(2001)058<0978:CCPWTL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Grabowski, W. W., X. Wu, M. Moncrieff, and W. D. Hall, 1998: Cloud resolving modeling of tropical cloud systems during phase III of GATE. Part II: Effects of resolution and the third spatial dimension. J. Atmos. Sci., 55, 3264–3282, doi:10.1175/1520-0469(1998)055<3264:CRMOCS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Houze, R. A., 1993: Cloud Dynamics.International Geophysics Series, Vol. 53, Academic Press, 573 pp.

  • Kain, J. S., and Coauthors, 2008: Some practical considerations regarding horizontal resolution in the first generation of operation convection-allowing NWP. Wea. Forecasting, 23, 931–952, doi:10.1175/WAF2007106.1.

    • Search Google Scholar
    • Export Citation

  • Langhans, W., J. Schmidli, and C. Schar, 2012: Bulk convergence of kilometer-scale simulations of moist convection over complex terrain. J. Atmos. Sci., 69, 2207–2228, doi:10.1175/JAS-D-11-0252.1.

    • Search Google Scholar
    • Export Citation

  • Lebo, Z. J., and H. Morrison, 2014: Dynamical effects of aerosol perturbations on simulated idealized squall lines. Mon. Wea. Rev., 142, 991–1009, doi:10.1175/MWR-D-13-00156.1.

    • Search Google Scholar
    • Export Citation

  • Markowski, P., and Y. Richardson, 2010: Mesoscale Meteorology in Midlatitudes.Wiley-Blackwell, 407 pp.

  • Morrison, H., 2015a: Impacts of updraft size and dimensionality on the perturbation pressure and vertical velocity in cumulus convection. Part I: Simple, generalized analytic solutions. J. Atmos. Sci., doi:10.1175/JAS-D-15-0040.1, in press.

    • Search Google Scholar
    • Export Citation

  • Morrison, H., 2015b: Impacts of updraft size and dimensionality on the perturbation pressure and vertical velocity in cumulus convection. Part II: Comparison of theoretical and numerical simulations and fully dynamical simulations. J. Atmos. Sci., doi:10.1175/JAS-D-15-0041.1, in press.

    • Search Google Scholar
    • Export Citation

  • Morrison, H., G. Thompson, and V. Tatarskii, 2009: Impact of cloud microphysics on the development of trailing stratiform precipitation in a simulated squall line: Comparison of one- and two-moment schemes. Mon. Wea. Rev., 137, 991–1007, doi:10.1175/2008MWR2556.1.

    • Search Google Scholar
    • Export Citation

  • Morrison, H., S. A. Tessendorf, J. Ikeda, and G. Thompson, 2012: Sensitivity of a simulated midlatitude squall line to parameterization of raindrop breakup. Mon. Wea. Rev., 140, 2437–2460, doi:10.1175/MWR-D-11-00283.1.

    • Search Google Scholar
    • Export Citation

  • Morrison, H., A. Morales, and C. Villanueva-Birriel, 2015: Concurrent sensitivities of an idealized deep convective storm to parameterization of microphysics, horizontal grid resolution, and environmental static stability. Mon. Wea. Rev., 143, 2082–2104, doi:10.1175/MWR-D-14-00271.1.

    • Search Google Scholar
    • Export Citation

  • Muhlbauer, A., and Coauthors, 2013: Reexamination of the state of the art of cloud modeling shows real improvements. Bull. Amer. Meteor. Soc., 94, ES45–ES48, doi:10.1175/BAMS-D-12-00188.1.

    • Search Google Scholar
    • Export Citation

  • Petch, J. C., and M. E. B. Gray, 2001: Sensitivity studies using a cloud-resolving model simulation of the tropical west Pacific. Quart. J. Roy. Meteor. Soc., 127, 2287–2306, doi:10.1002/qj.49712757705.

    • Search Google Scholar
    • Export Citation

  • Petch, J. C., A. R. Brown, and M. E. B. Gray, 2002: The impact of horizontal resolution on the simulations of convective development over land. Quart. J. Roy. Meteor. Soc., 128, 2031–2044, doi:10.1256/003590002320603511.

    • Search Google Scholar
    • Export Citation

  • Randall, D., M. Khairoutdinov, A. Arakawa, and W. Grabowski, 2003: Breaking the cloud parameterization deadlock. Bull. Amer. Meteor. Soc., 84, 1547–1564, doi:10.1175/BAMS-84-11-1547.

    • Search Google Scholar
    • Export Citation

  • Rotunno, R., Y. Chen, W. Wang, C. Davis, J. Dudhia, and G. J. Holland, 2009: Large-eddy simulation of an idealized tropical cyclone. Bull. Amer. Meteor. Soc., 90, 1783–1788, doi:10.1175/2009BAMS2884.1.

    • Search Google Scholar
    • Export Citation

  • Schwartz, C. S., and Coauthors, 2009: Next-day convection-allowing WRF model guidance: A second look at 2-km versus 4-km grid spacing. Mon. Wea. Rev., 137, 3351–3372, doi:10.1175/2009MWR2924.1.

    • Search Google Scholar
    • Export Citation

  • Simpson, J., 1971: On cumulus entrainment and one-dimensional models. J. Atmos. Sci., 28, 449–455, doi:10.1175/1520-0469(1971)028<0449:OCEAOD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Skamarock, W. C., 2004: Evaluating mesoscale NWP models using kinetic energy spectra. Mon. Wea. Rev., 132, 3019–3032, doi:10.1175/MWR2830.1.

    • Search Google Scholar
    • Export Citation

  • Skamarock, W. C., and Coauthors, 2008: A description of the Advanced Research WRF version 3. NCAR Tech. Note NCAR/TN-475+STR, 113 pp. [Available online at http://www.mmm.ucar.edu/wrf/users/docs/arw_v3_bw.pdf.]

  • Stein, T. H. M., R. J. Hogan, P. A. Clark, C. E. Halliwell, K. E. Hanley, H. W. Lean, J. C. Nicol, and R. S. Plant, 2015: The DYMECS project: A statistical approach for the evaluation of convective storms in high-resolution NWP models. Bull. Amer. Meteor. Soc., 96, 939–952, doi:10.1175/BAMS-D-13-00279.1.

    • Search Google Scholar
    • Export Citation

  • Tao, W., and Coauthors, 2009: A multiscale modeling system: Developments, applications and critical issues. Bull. Amer. Meteor. Soc., 90, 515–534, doi:10.1175/2008BAMS2542.1.

    • Search Google Scholar
    • Export Citation

  • VandenBerg, M. A., M. C. Coniglio, and A. J. Clark, 2014: Comparison of next-day convection-allowing forecasts of storm motion on 1- and 4-km grids. Wea. Forecasting, 29, 878–893, doi:10.1175/WAF-D-14-00011.1.

    • Search Google Scholar
    • Export Citation

  • Verelle, A., D. Ricard, and C. Lac, 2014: Sensitivity of high-resolution idealized simulations of thunderstorms to horizontal resolution and turbulence parameterization. Quart. J. Roy. Meteor. Soc., 141, 433–448, doi:10.1002/qj.2363.

    • Search Google Scholar
    • Export Citation

  • Wang, H., W. C. Skamarock, and G. Feingold, 2009: Evaluation of scalar advection schemes in the Advance Research WRF Model using large-eddy simulations of aerosol–cloud interactions. Mon. Wea. Rev., 137, 2547–2558, doi:10.1175/2009MWR2820.1.

    • Search Google Scholar
    • Export Citation

  • Weisman, M. L., W. C. Skamarock, and J. B. Klemp, 1997: The resolution dependence of explicitly modeled convective systems. Mon. Wea. Rev., 125, 527–548, doi:10.1175/1520-0493(1997)125<0527:TRDOEM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Weisman, M. L., C. Davis, W. Wang, K. W. Manning, and J. B. Klemp, 2008: Experiences with 0–36-h explicit convective forecasts with the WRF-ARW Model. Wea. Forecasting, 23, 407–437, doi:10.1175/2007WAF2007005.1.

    • Search Google Scholar
    • Export Citation

  • Wyngaard, J. C., 2004: Toward numerical modeling in the “terra incognita.” J. Atmos. Sci., 61, 1816–1826, doi:10.1175/1520-0469(2004)061<1816:TNMITT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Ziegler, C. L., E. R. Mansell, J. M. Straka, D. R. MacGorman, and D. W. Burgess, 2010: The impact of spatial variations of low-level stability on the life cycle of a simulated supercell storm. Mon. Wea. Rev., 138, 1738–1766, doi:10.1175/2009MWR3010.1.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 1055 346 30
PDF Downloads 659 274 23