Editorial Type:
Article
Article Type:
Research Article

Numerical Simulation of Transitions in Boundary Layer Convective Structures in a Lake-Effect Snow Event

Kevin A. Cooper Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, Rapid City, South Dakota

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Mark R. Hjelmfelt Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, Rapid City, South Dakota

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Russell G. Derickson Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, Rapid City, South Dakota

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David A. R. Kristovich Atmospheric Environment Section, Illinois State Water Survey, Champaign, Illinois

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Neil F. Laird Atmospheric Environment Section, Illinois State Water Survey, Champaign, Illinois

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Print Publication:
01 Sep 2000
DOI:
https://doi.org/10.1175/1520-0493(2000)128<3283:NSOTIB>2.0.CO;2
Page(s):
3283–3295
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Abstract

Numerical simulations are used to study transitions between boundary layer rolls and more cellular convective structures observed during a lake-effect snow event over Lake Michigan on 17 December 1983. Weak lake-effect nonroll convection was observed near the eastern (downwind) shore preceding passage of a secondary cold front. After frontal passage horizontal wind speeds in the convective boundary layer increased, with subsequent development of linear convective patterns. Thereafter the convective pattern became more three-dimensional as low-level wind speeds decreased. Little directional shear was observed in any of the wind profiles. Numerical simulations with the Advanced Regional Prediction System model were initialized with an upwind sounding and radar-derived wind profiles corresponding to each of the three convective structure regimes. Model-derived reflectivity fields were in good agreement with the observed regimes. These simulations differed primarily in the initial wind speed profiles, and suggest that wind speed and shear in the lower boundary layer are critical in determining the linearity of convection. Simulation with an upwind-overlake wind profile, with strong low-level winds, produced the most linear model reflectivity structure. Fluxes and measures of shear-to-buoyancy ratio for this case were comparable to observations.

Model sensitivity tests were conducted to determine the importance of low-level wind speed and speed shear in determining the linearity of convection. Results are consistent with trends expected from ratios of buoyancy to shear (but not proposed numerical threshold values). Eliminating all directional shear from the initial wind profile for the most linear case did not reduce the degree of linearity, thus showing that directional shear is not a requirement for rolls in lake-effect convection. Elimination of clouds (principally latent heating) reduced the vertical velocities by about 50%. It was found that variations in wind speed shear below 200-m height played a major role in determining the degree of linearity of the convection.

Corresponding author address: Dr. Mark R. Hjelmfelt, Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, 501 East Saint Joseph Street, Rapid City, SD 57701-3995.

Abstract

Numerical simulations are used to study transitions between boundary layer rolls and more cellular convective structures observed during a lake-effect snow event over Lake Michigan on 17 December 1983. Weak lake-effect nonroll convection was observed near the eastern (downwind) shore preceding passage of a secondary cold front. After frontal passage horizontal wind speeds in the convective boundary layer increased, with subsequent development of linear convective patterns. Thereafter the convective pattern became more three-dimensional as low-level wind speeds decreased. Little directional shear was observed in any of the wind profiles. Numerical simulations with the Advanced Regional Prediction System model were initialized with an upwind sounding and radar-derived wind profiles corresponding to each of the three convective structure regimes. Model-derived reflectivity fields were in good agreement with the observed regimes. These simulations differed primarily in the initial wind speed profiles, and suggest that wind speed and shear in the lower boundary layer are critical in determining the linearity of convection. Simulation with an upwind-overlake wind profile, with strong low-level winds, produced the most linear model reflectivity structure. Fluxes and measures of shear-to-buoyancy ratio for this case were comparable to observations.

Model sensitivity tests were conducted to determine the importance of low-level wind speed and speed shear in determining the linearity of convection. Results are consistent with trends expected from ratios of buoyancy to shear (but not proposed numerical threshold values). Eliminating all directional shear from the initial wind profile for the most linear case did not reduce the degree of linearity, thus showing that directional shear is not a requirement for rolls in lake-effect convection. Elimination of clouds (principally latent heating) reduced the vertical velocities by about 50%. It was found that variations in wind speed shear below 200-m height played a major role in determining the degree of linearity of the convection.

Corresponding author address: Dr. Mark R. Hjelmfelt, Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, 501 East Saint Joseph Street, Rapid City, SD 57701-3995.

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  • Agee, E. M., 1987: Mesoscale cellular convection over the oceans. Dyn. Atmos. Oceans,10, 317–341.

  • Atkinson, B. W., 1981: Meso-Scale Atmospheric Circulations. Academic Press, 495 pp.

  • ——, and J. W. Zhang, 1996: Mesoscale shallow convection in the atmosphere. Rev. Geophys.,34, 403–431.

  • Braham, R. R., Jr., 1986: Cloud and motion fields in open-cell convection over Lake Michigan. Preprints, Joint Sessions—23d Conf. on Radar Meteorology and Conf. on Cloud Physics, Snowmass, CO, Amer. Meteor. Soc., JP202–JP205.

  • ——, and R. D. Kelly, 1982: Lake-effect snow storms on Lake Michigan, USA. Cloud Dynamics, E. M. Agee and T. Asai, Eds., D. Reidel, 87–101.

  • Grossman, R. L., 1982: An analysis of vertical velocity spectra obtained in the BOMEX fair-weather, trade-wind boundary layer. Bound.-Layer Meteor.,23, 323–357.

  • Hjelmfelt, M. R., 1990: Numerical study of the influence of environmental conditions on lake-effect snowstorms over Lake Michigan. Mon. Wea. Rev.,118, 138–150.

  • ——, and R. R. Braham Jr., 1983: Numerical simulation of the airflow over Lake Michigan for a major lake-effect snow event. Mon. Wea. Rev.,111, 205–219.

  • Kelly, R. D., 1982: A single Doppler radar study of horizontal-roll convection in a lake-effect snow storm. J. Atmos. Sci.,39, 1521–1531.

  • ——, 1984: Horizontal roll and boundary-layer interrelationships observed over Lake Michigan. J. Atmos. Sci.,41, 1816–1826.

  • ——, 1986: Mesoscale frequencies and seasonal snowfalls for different types of Lake Michigan snow storms. J. Climate Appl. Meteor.,25, 308–321.

  • Koschmieder, E. L., 1993: Bénard Cells and Taylor Vortices. Cambridge University Press, 337 pp.

  • Kristovich, D. A. R., 1991: The three-dimensional flow fields of boundary layer rolls observed during lake-effect snowstorms. Ph.D. thesis, University of Chicago, 178 pp. [Available from University of Chicago, 501 E. St. Ellis, Chicago, IL 60637.].

  • ——, 1993: Mean circulations of boundary-layer rolls in lake-effect snow storms. Bound.-Layer Meteor.,63, 293–315.

  • ——, and R. A. Steve III, 1995: A satellite study of cloud-band frequencies over the Great Lakes. J. Appl. Meteor.,34, 2083–2090.

  • ——, and N. F. Laird, 1998: Observations of widespread lake-effect cloudiness: Influences of upwind conditions and lake surface temperatures. Wea. Forecasting,13, 811–821.

  • ——, ——, M. R. Hjelmfelt, R. G. Derickson, and K. A. Cooper, 1999: Transitions in boundary layer meso-γ convective structures: An observational case study. Mon. Wea. Rev.,127, 2895–2909.

  • Lin, Y. L., R. D. Farley, and H. D. Orville, 1983: Bulk parameterization of the snow field in a cloud model. J. Climate Appl. Meteor.,22, 1065–1092.

  • Rao, G.-S., and E. M. Agee, 1996: Large eddy simulation of turbulent flow in a marine convective boundary layer with snow. J. Atmos. Sci.,53, 86–100.

  • Smith, P. L., Jr., C. G. Myers, and H. D. Orville, 1975: Radar reflectivity factor calculations in numerical cloud models using bulk parameterization of precipitation. J. Appl. Meteor.,14, 1156–1165.

  • Sun, W. Y., and C.-Z. Chang, 1986: Diffusion model for a convective layer. Part I: Numerical simulation of convective boundary layer. J. Climate Appl. Meteor.,25, 1445–1453.

  • Sykes, R. I., and D. S. Henn, 1989: Large-eddy simulations of turbulent sheared convection. J. Atmos. Sci.,46, 1106–1118.

  • ——, W. S. Lewellen, and D. S. Henn, 1988: A numerical study of the development of cloud-street spacing. J. Atmos. Sci.,45, 2556–2569.

  • Tao, W.-K., and J. Simpson, 1993: Goddard cumulus ensemble model. Part 1: Model description. Terr. Atmos., Oceanic Sci.,4, 35–72.

  • Weckwerth, T. M., J. W. Wilson, and R. W. Wakimoto, 1996: Thermodynamic variability within the convective boundary layer due to horizontal convective rolls. Mon. Wea. Rev.,5, 769–784.

  • ——, ——, ——, and N. A. Crook, 1997: Horizontal convective rolls:Determining the environmental conditions supporting their existence and characteristics. Mon. Wea. Rev.,125, 505–526.

  • ——, T. W. Horst, and J. Wilson, 1999: An observational study of the evolution of horizontal convective rolls. Mon. Wea. Rev.,127, 2160–2179.

  • Wilson, J. W., T. M. Weckwerth, J. Vivekanandan, R. M. Wakimoto, and R. W. Russell, 1994: Boundary layer clear-air radar echoes:Origins of echoes and accuracy of derived winds. J. Atmos. Oceanic Technol.,11, 1184–1206.

  • Xue, M., K. K. Droegemeier, and V. Wong, 1995a: The advanced regional prediction system and real-time storm-scale weather prediction. Preprints, Int. Workshop on Limited-area and Variable Resolution Models, Beijing, China, WMO and Amer. Meteor. Soc.

  • ——, ——, ——, A. Shapiro, and K. Brewster, 1995b: ARPS version 4.0 user’s guide. Center for Data Analysis and Prediction of Storms, 380 pp. [Available from the Center of Data Analysis and Prediction of Storms, University of Oklahoma, Norman, OK 73072.].

  • ——, J. Zong, and K. K. Droegemeier, 1996: Parameterization of PBL turbulence in a multiscale nonhydrostatic model. Preprints, 11th Conf. on Numerical Weather Prediction, Norfolk, VA, Amer. Meteor. Soc., 363–365.

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