Advertisement

Boundary-Layer Meteorology

, Volume 23, Issue 4, pp 449–472 | Cite as

Turbulence characteristics in a near neutrally stratified urban atmosphere

  • Ulf Högström
  • Hans Bergström
  • Hans Alexandersson
Article

Abstract

Turbulence measurements from the city of Uppsala, Sweden, are analysed. Measurements were taken at two sites: one in the central area, ca. 6 m above roof level, the average building height being ca. 15 m; the other at ca. 8 and 50 m above the ground on a tower situated 100 m downwind of a sharp discontinuity between the densely built-up urban area and flat grass-covered land. The average stability was close to neutral, the range being -0.2 < z/L < 0.2. The main emphasis of the study is on the non-dimensional standard deviations of the velocity components Σ i /u*t and on the corresponding non-dimensional energy spectra, u*t being a local velocity scale defined as √Τ i /ρ(Τ l is the local momentum flux). Comparison with results obtained from surface-layer measurements at ‘ideal sites’ (with u*, being the ordinary friction velocity) shows good general agreement. The most complete agreement is found for the tower 50 m measurements, a result which is notable as this measurement point is found to be within a distinctly transitional zone between the urban and post-urban boundary layers. The results from the central city measurement point are also fairly close to the ‘ideal’ results, the deviations found being small in view of the fact that the site is probably inside the layer in which the roughness elements (the buildings) have direct influence. The measurements at the tower 8 m level show certain distinct deviations from ideal results: all three Σ i /u*l, are higher by ca. 10%, the excessive energy being found at the low frequency end of the spectrum. Arguments are presented for this feature to be due to a spectral lag effect.

Keywords

Roughness Element Building Height Urban Atmosphere Average Stability Roof Level 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Batchelor, G. K.: 1953, The Theory of Homogeneous Turbulence, Cambridge at the University Press, 197 pp.Google Scholar
  2. Faxén, T., Smedman-Högström, A.-S., and Högström, gnU.: 1978, ‘The Meteorological Field Project at the Wind Energy Test Site Kalkugnen, Sweden’, Met. Inst. Uppsala, Report No. 51.Google Scholar
  3. Garrat, J. R. (1980), ‘Surface Influence upon Vertical Profiles in the Atmospheric Near-Surface Layer’, Quart. J. Roy. Meteorol. Soc. 106, 803–819.Google Scholar
  4. Högström, U. and Smedman-Högström, A.-S.: 1974, ‘Turbulence Mechanisms at an Agricultural Site’, Boundary-Layer Meteorol. 7, 373–389.Google Scholar
  5. Högström, U., Taesler, R., Karlsson, S., Enger, L., and Smedman-Högström, A.-S.: 1978, ‘The Uppsala Urban Meteorology Project’, Boundary-Layer Meteorol. 15, 69–80.Google Scholar
  6. Högström, U., Enger, L., and Knudsen, E.: 1980, ‘A Complete System for Probing the Detailed Structure of Atmospheric Boundary Layer Flow’, Met. Inst. Uppsala, Reports No. 60.Google Scholar
  7. Högström, U.: 1982, ‘A Critical Evaluation of the Aero-Dynamical Error of a Turbulence Instrument’, submitted to J. Appl. Meteorol. Google Scholar
  8. Kaimal, J. C., Wyngaard, J. C., Izumi, Y., and Coté, O. R.: 1972, ‘Spectral Characteristics of Surface Layer Turbulence’, Quart. J. Roy. Meteorol. Soc. 98, 563–589.Google Scholar
  9. Karlsson, S.: 1981, ‘Analysis of Wind Profile Data from an Urban-Rural Interface Site’, Met. Inst. Uppsala, Reports No. 58.Google Scholar
  10. Lumley, J. and Panofsky, H.: 1964, The Structure of Atmospheric Turbulence, John Wiley, New York.Google Scholar
  11. Monin, A. S. and Yaglom, A. M.: 1971, Statistical Fluid Mechanics, Vol. 1, The MIT Press, 769 pp.Google Scholar
  12. Raupach, M.: 1979, ‘Anomalies in Flux-Gradient Relationships over Forests’, Boundary-Layer Meteorol. 16, 467–486.Google Scholar
  13. Smedman-Högström, A.-S. and Högström, U.: 1982, Spectral Characteristics of the Surface Layer at an Heteorogeneous Site, cm(to be published).Google Scholar
  14. Smedman-Högström, A.-S. and Högström, U.: 1978, ‘A Practical Method for Determining Wind Frequency Distributions for the Lowest 200 m from Routine Meteorological Data’, J. Appl. Meteorol. 17, 942–954.Google Scholar
  15. Taesler, R.: 1981, ‘Studies of the Development and Thermal Structure of the Urban Boundary Layer in Uppsala’, Met. Inst. Uppsala, Reports No. 61.Google Scholar
  16. Taesler, R. and Karlsson, S.: 1981, ‘Power Law Estimates of the Urban Wind Profile’, Met. Inst. Uppsala, Reports No. 59.Google Scholar

Copyright information

© D. Reidel Publishing Co 1982

Authors and Affiliations

  • Ulf Högström
    • 1
  • Hans Bergström
    • 1
  • Hans Alexandersson
    • 1
  1. 1.Department of MeteorologyUppsalaSweden

Personalised recommendations