An Observational and Numerical Study of a Sheared, Convective Boundary Layer. Part I: Phoenix II Observations, Statistical Description, and Visualization

Jeanne M. Schneider National Severe Storms Laboratory, Norman, Oklahoma

Search for other papers by Jeanne M. Schneider in
Current site
Google Scholar
PubMed
Close
and
Douglas K. Lilly School of Meteorology, University of Oklahoma, Norman, Oklahoma

Search for other papers by Douglas K. Lilly in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Four-dimensional velocity fields derived from dual Doppler radar observations are the basis of a description and statistical analysis of a convective, sheared planetary boundary layer during an afternoon over the High Plains of eastern Colorado. Mean velocities and momentum fluxes are calculated directly from the radar data and are verified with aircraft and tower data. Perturbation pressure and buoyancy fields are recovered for turbulent kinetic energy budgets, and for estimates of horizontal heat advection across the analysis area. The surface layer and lowest third of the observed boundary layer were similar to minimally sheared convective boundary layers, but there were significant differences in the upper two-thirds of the boundary layer. An overrunning residual mountain boundary layer merged with the locally generated convective boundary layer, producing a deep, continuously sheared layer of turbulent activity. Computer visualization reveals a complicated flow characterized by clusters of vortical structures extending well into the slightly stable overrunning region, frequently dominated by clusters of large, long-lived vortices. First- and second-order statistics vary with time of day and averaging volume, suggesting that appropriate parameterizations of similar boundary layers should be functions of the required spatial and temporal scales and mesoscale environment. A number of common simplifying assumptions, scalings, and parameterizations employed for purely convective boundary layers would be inappropriate for this flow.

Corresponding author address: Jeanne M. Schneider, USDA-ARS, Grazinglands Research Laboratory, 7207 W. Cheyenne St., El Reno, OK 73036.

Email: jschneider@grl.ars.usda.gov

Abstract

Four-dimensional velocity fields derived from dual Doppler radar observations are the basis of a description and statistical analysis of a convective, sheared planetary boundary layer during an afternoon over the High Plains of eastern Colorado. Mean velocities and momentum fluxes are calculated directly from the radar data and are verified with aircraft and tower data. Perturbation pressure and buoyancy fields are recovered for turbulent kinetic energy budgets, and for estimates of horizontal heat advection across the analysis area. The surface layer and lowest third of the observed boundary layer were similar to minimally sheared convective boundary layers, but there were significant differences in the upper two-thirds of the boundary layer. An overrunning residual mountain boundary layer merged with the locally generated convective boundary layer, producing a deep, continuously sheared layer of turbulent activity. Computer visualization reveals a complicated flow characterized by clusters of vortical structures extending well into the slightly stable overrunning region, frequently dominated by clusters of large, long-lived vortices. First- and second-order statistics vary with time of day and averaging volume, suggesting that appropriate parameterizations of similar boundary layers should be functions of the required spatial and temporal scales and mesoscale environment. A number of common simplifying assumptions, scalings, and parameterizations employed for purely convective boundary layers would be inappropriate for this flow.

Corresponding author address: Jeanne M. Schneider, USDA-ARS, Grazinglands Research Laboratory, 7207 W. Cheyenne St., El Reno, OK 73036.

Email: jschneider@grl.ars.usda.gov

Save
  • Armijo, L., 1969: A theory for the determination of wind and precipitation velocities with Doppler radars. J. Atmos. Sci.,26, 570–573.

  • Arritt, R. W., J. M. Wilczak, and G. S. Young, 1992: Observations and numerical modeling of an elevated mixed layer. Mon. Wea. Rev.,120, 2869–2880.

  • Brümmer, B., 1985: Structure, dynamics, and energetics of boundary layer rolls from KonTur aircraft observations. Contrib. Atmos. Phys.,58, 237–254.

  • Businger, J. A., J. C. Wyngaard, Y. Izumi, and E. F. Bradley, 1971: Flux-profile relationships in the atmospheric surface layer. J. Atmos. Sci.,28, 181–189.

  • Caughey, S. J., and J. C. Wyngaard, 1979: The turbulence kinetic energy budget in convective conditions. Quart. J. Roy. Meteor. Soc.,105, 231–239.

  • Doviak, R. J., P. S. Ray, R. G. Strauch, and L. J. Miller, 1976: Error estimation in wind fields derived from dual-Doppler radar measurement. J. Appl. Meteor.,15, 868–878.

  • Einaudi, F., and J. J. Finnigan, 1993: Wave–turbulence dynamics in the stably stratified boundary layer. J. Atmos. Sci.,50, 1841–1864.

  • Etling, D., and R. A. Brown, 1993: Roll vortices in the planetary boundary layer. A review. Bound.-Layer Meteor.,65, 215–248.

  • Frisch, A. S., and S. F. Clifford, 1974: A study of convection capped by a stable layer using Doppler radar and acoustic echo sounders. J. Atmos. Sci.,31, 1622–1628.

  • Frisch, U., and S. A. Orszag, 1990: Turbulence: Challenges for theory and experiment. Phys. Today,43, 24–32.

  • Gal-Chen, T., 1978: A method for the initialization of the anelastic equations: Implications for matching models with observations. Mon. Wea. Rev.,106, 587–606.

  • ——, 1982: Errors in fixed and moving frame of references: Applications for conventional and Doppler radar analysis. J. Atmos. Sci.,39, 2279–2300.

  • ——, and J. C. Wyngaard, 1982: Effects of volume averaging on the line spectra of vertical velocity from mutliple-Doppler radar observations. J. Appl. Meteor.,21, 1881–1890.

  • ——, and R. A. Kropfli, 1984: Buoyancy and pressure perturbations derived from dual-Doppler radar observations of the planetary boundary layer: Applications for matching models with observations. J. Atmos. Sci.,41, 3007–3020.

  • Hane, E. E., and B. C. Scott, 1978: Temperature and pressure perturbations within convective clouds derived from detailed air motion information: Prelimary testing. Mon. Wea. Rev.,106, 656–661.

  • Hanna, S. R., 1982: Applications in air pollution modeling. Atmospheric Turbulence and Air Pollution Modeling, F. T. M. Nieuwstadt and H. van Dop, Eds., D. Reidel, 275–276.

  • Holtslag, A. A. M., and C.-H. Moeng, 1991: Eddy diffusivity and countergradient transport in the convective atmospheric boundary layer. J. Atmos. Sci.,48, 1690–1698.

  • Jury, M., M. Rouault, S. Weeks, and M. Schormann, 1997: Atmospheric boundary-layer fluxes and structure across a land–sea transition zone in south-eastern Africa. Bound.-Layer Meteor.,83, 311–330.

  • Kaimal, J. C., and J. E. Gaynor, 1983: The Boulder Atmospheric Observatory. J. Climate Appl. Meteor.,22, 863–880.

  • ——, R. A. Eversole, D. H. Lenschow, B. B. Stankov, P. H. Kahn, and J. A. Businger, 1982: Spectral characteristics of the convective boundary layer over uneven terrain. J. Atmos. Sci.,39, 1098–1113.

  • Kropfli, R. A., and P. H. Hildebrand, 1980: Three-dimensional wind measurements in the optically clear planetary boundary layer with dual-Doppler radar. Radio Sci.,15, 283–296.

  • Lanicci, J. M., and T. T. Warner, 1991a: A synoptic climatology of the elevated mixed-layer inversion over the southern Great Plains in spring. Part I: Structure, dynamics, and seasonal evolution. Wea. Forecasting,6, 181–197.

  • ——, and ——, 1991b: A synoptic climatology of the elevated mixed-layer inversion over the southern Great Plains in spring. Part II:The life cycle of the lid. Wea. Forecasting,6, 198–213.

  • ——, and ——, 1991c: A synoptic climatology of the elevated mixed-layer inversion over the southern Great Plains in spring. Part III:Relationship to severe-storms climatology. Wea. Forecasting,6, 214–226.

  • Lee, S., 1987: Turbulence statistics derived from the portable automated mesonet (PAM), dual-Doppler radar, and instrumented tower. M.S. thesis, School of Meteorology, University of Oklahoma, 135 pp. [Available from the School of Meteorology, University of Oklahoma, Norman, OK 73019.].

  • Leise, J. A., 1981: A multidimensional scale-telescoped filter and data extension package. NOAA Tech. Memo. ERL/WPL-82, 20 pp. [Available from Environmental Technology Laboratory, 325 Broadway, Boulder, CO 80303.].

  • LeMone, M. A., 1973: The structure and dynamics of horizontal roll vorticies in the planetary boundary layer. J. Atmos. Sci.,30, 1077–1091.

  • Lenschow, D. H., J. C. Wyngaard, and W. T. Pennell, 1980: Mean-field and second-moment budgets in a baroclinic, convective boundary layer. J. Atmos. Sci.,37, 1313–1326.

  • Lin, J.-J., 1988: Spectral and energy budget analysis of the Phoenix II aircraft data. M.S. thesis, School of Meteorology, University of Oklahoma, 59 pp. [Available from the School of Meteorology, University of Oklahoma, Norman, OK 73019.].

  • Ludwig, F. L., R. L. Street, J. M. Schneider, and K. R. Kostigan, 1996: Analysis of small-scale patterns of atmospheric motion in a sheared, convective boundary layer. J. Geophys. Res.,101, 9391–9411.

  • Lunsford, A. C., 1986: A study of afternoon and evening pressure spectra for periods of two seconds to thirty minutes. M.S. thesis, School of Meteorology, University of Oklahoma, 191 pp. [Available from the School of Meteorology, University of Oklahoma, Norman, OK 73019.].

  • Maryon, R. H., 1990: A statistical representation of sub-grid variation in mixing-length models of the boundary layer. Bound.-Layer Meteor.,53, 371–399.

  • Moeng, C.-H., and J. C. Wyngaard, 1989. Evaluation of turbulent transport and dissipation closures in second-order modeling. J. Atmos. Sci.,46, 2311–2330.

  • ——, and R. Rotunno, 1990: Vertical-velocity skewness in the buoyancy-driven boundary layer. J. Atmos. Sci.,47, 1149–1162.

  • Parsons, D. B., C. G. Mohr, and T. Gal-Chen, 1987: A severe frontal rainband. Part III: Derived thermodynamic structure. J. Atmos. Sci.,44, 1615–1631.

  • Reiter, E. R., and M. Tang, 1984: Plateau effects on diurnal circulation patterns. Mon. Wea. Rev.,112, 638–651.

  • Schneider, J. M., 1991: Dual Doppler measurement of a sheared, convective boundary layer. Ph.D. dissertation, University of Oklahoma, UMI 9128656, 133 pp. [Available from the School of Meteorology, University of Oklahoma, Norman, OK 73019.].

  • Sorbjan, Z., 1989: Structure of the Atmospheric Boundary Layer. Prentice Hall, 317 pp.

  • Stensrud, D. J., 1993: Elevated residual layers and their influence on surface boundary-layer evolution. J. Atmos. Sci.,50, 2284–2293.

  • Stull, R. B., 1988: An Introduction to Boundary Layer Meteorology. Kluwer Academic, 666 pp.

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

  • Tang, M., and E. R. Reiter, 1984: Plateau monsoons of the Northern Hemisphere: A comparison between North America and Tibet. Mon. Wea. Rev.,112, 617–637.

  • Wilczak, J. M., and J. W. Glendening, 1988: Observations and mixed-layer modeling of a terrain-induced mesoscale gyre: The Denver Cyclone. Mon. Wea. Rev.,116, 2688–2711.

  • ——, and T. W. Christian, 1990: Case study of an orographically induced mesoscale vortex (Denver Cyclone). Mon. Wea. Rev.,118, 1082–1102.

  • Williams, A. C., and J. M. Hacker, 1993: Interactions between coherent eddies in the lower convective boundary layer. Bound.-Layer Meteor.,64, 55–74.

  • Wilson, D. K., 1996: Empirical orthogonal function analysis of the weakly convective atmospheric boundary layer. Part I: Eddy structures. J. Atmos. Sci.,53, 801–823.

  • ——, and J. C. Wyngaard, 1996: Empirical orthogonal function analysis of the weakly convective atmospheric boundary layer. Part II: Eddy energetics. J. Atmos. Sci.,53, 824–841.

  • Wyngaard, J. C., 1973: On surface layer turbulence. Workshop on Micrometeorology, D. A. Haugen, Ed., Amer. Meter. Soc., 101–149.

  • ——, 1983: Lectures on the planetary boundary layer. Mesoscale Meteorology Models, Observations, and Theories, D. K. Lilly and T. Gal-Chen, Eds., Reider, 603–651.

  • ——, 1992: Atmospheric turbulence. Annu. Rev. Fluid Mech.,24, 205–233.

  • Young, G., 1988a: Turbulence structure of the convective boundary layer. Part I: Variability of normalized turbulence statistics. J. Atmos. Sci.,45, 719–726.

  • ——, 1988b: Turbulence structure of the convective boundary layer. Part II: Phoenix 78 aircraft observations of thermals and their environment. J. Atmos. Sci.,45, 727–735.

  • Zabusky, N. J., and Coauthors, 1993: Visiometrics, juxtaposition and modeling. Phys. Today,46, 24–31.

  • Zhong, S., and J. C. Doran, 1995: A modeling study of the effects of inhomogeneous surface fluxes on boundary-layer properties. J. Atmos. Sci.,52, 3129–3142.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 85 17 4
PDF Downloads 44 7 0