Boundary-Layer Meteorology

, Volume 95, Issue 3, pp 437–456 | Cite as

Simulated Airborne Flux Measurements in a LES generated Convective Boundary Layer

  • M. Schröter
  • J. Bange
  • S. Raasch
Article

Abstract

One aim of past boundary-layer experiments with aircraft was the determination of areally averaged heat fluxes. In spite ofsophisticated instrumentation the measured fluxes extrapolated to the ground differed significantly from fluxes measured directly at ground stations. This studypresents simulated sensible heat flux measurements with aircraft flightsthrough a synthetic convective boundary layer created by a401 × 401 × 42 cubic-grid large eddy simulation (LES) with agrid spacing of 50 m. After some considerations with respect to necessary measurement lengths using results ofLenschow and Stankov (1986 – J. Atmos. Sci.43, 1198–1209), simulated measurementcampaigns were carried out in three modelruns. During each model run five sets ofmeasurement runs were carried out successively.During each set of runs 10 aircraftflew at 10 altitudes with a ground speedof 100 m s-1 simultaneously throughtime and space. In total, 150 legs were carried out, 15 at each flight level. The resulting`measured' heat fluxes were compared withthose of the `true' flux profiles obtaineddirectly from the ensemble-averagedLES-generated data. No significant systematic error between `measured' and `true' profiles was observed. Furthermore, the comparison of the resulting relative error with the theory ofLenschow and Stankov showed a good agreement at allmeasurement levels.

Large-eddy simulation Convective boundary layer Spectra Averaging Length Airborne Flux Measurements 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Ahlberg, J. H., Nilson, E. N., and Walsh, J. L.: 1967, The Theory of Splines and their Applications, Academic Press, New York/London, 284 pp.Google Scholar
  2. André, J. C., Goutorbe, J.-P., and Perrier, A.: 1986, ‘HAPEX-MOBILHY:A Hydrologic Atmospheric Experiment for the Study of Water Budget and Evaporation Flux at the Climate Scale’, Bull. Amer. Meteorol. Soc. 67, 138–144.Google Scholar
  3. Andren, A., Brown, A. R., Graf, J., Moeng, C.-H., Nieuwstadt, F. T. M., and Schumann, U.: 1994, ‘Large-Eddy Simulation of a Neutrally Stratified Boundary Layer: A Comparison of Four Computer Codes’, Quart. J. Roy. Meteorol. Soc. 120, 1457–1484.Google Scholar
  4. Betts, A. K., Desjardins, R. L., and MacPherson, J. I.: 1992, ‘Budget Analysis of the Boundary Layer Grid Flights during FIFE 1987’, J. Geophys. Res. 97, 18,533–18,546.Google Scholar
  5. Betts, A. K., Desjardins, R. L., MacPherson, J. I., and Kelly, R. D.: 1990, ‘Boundary-Layer Heat and Moisture Budgets from FIFE’, Boundary-Layer Meteorol. 50, 109–137.Google Scholar
  6. Busch, U., Hofmann, M., Jacobi, C., and Roth, R.: 1990, ‘Errors in Aircraft Measurements of Turbulent Fluxes in a Boundary Layer with Strong Convection’, Phys. Chem. Earth 21, 393–397.Google Scholar
  7. Cai, X.-M. and Steyn, D. G.: 1996, ‘The von Kármán Constant Determined by Large Eddy Simulation’, Boundary-Layer Meteorol. 78, 143–164.Google Scholar
  8. Deardorff, J. W.: 1974, ‘Three-Dimensional Numerical Study of Turbulence in an Entraining Mixed Layer’, Boundary-Layer Meteorol. 7, 199–226.Google Scholar
  9. Desjardins, R. L., MacPherson, J. I., Schuepp, P. H., and Karanja, F.: 1989, ‘An Evaluation of Aircraft Flux Measurements of CO2, Water Vapor and Sensible Heat’, Boundary-Layer Meteorol. 47, 55–69.Google Scholar
  10. Doran, J. C., Shaw, W. J., and Hubbe, J. M.: 1995, ‘Boundary Layer Characteristics over Areas of Inhomogeneous Surface Fluxes’, J. Appl. Meteorol. 34, 559–571.Google Scholar
  11. Grossman, R. L.: 1992, ‘Sampling Errors in the Vertical Fluxes of Potential Temperature and Moisture Measured by Aircraft during FIFE’, J. Geophys. Res. 97, 18,439–18,443.Google Scholar
  12. Grunwald, J., Kalthoff, N., Corsmeier, U., and Fiedler, F.: 1996, ‘Comparison of Areally Averaged Turbulent Fluxes over Non-Homogeneous Terrain: Results from the EFEDA-Field Experiment’, Boundary-Layer Meteorol. 77, 105–134.Google Scholar
  13. Hauf, T.: 1984, ‘Turbulenzmessungen mit dem Forschungsflugzeug Falcon’, Meteorol. Rdsch. 37, 163–176.Google Scholar
  14. Kaimal, J. C. and Finnigan, J. J.: 1994, Atmospheric Boundary Layer Flows. Their Structure and Measurements. Oxford University Press, New York/Oxford, 289 pp.Google Scholar
  15. Kaimal, J. C., Wyngaard, J. C., Haugen, D. A., Coté, O. R., and Izumi, Y.: 1976, ‘Turbulence Struture in the Convective Boundary Layer’, J. Atmos. Sci. 33, 2152–2169.Google Scholar
  16. Kelly, R. D., Smith, E. A., and MacPherson, J. I.: 1992, ‘A Comparison of Surface Sensible and Latent Heat Fluxes from Aircraft and Surface Measurements in FIFE 1987’, J. Geophys. Res. 97, 18,445–18,453.Google Scholar
  17. Kolmogorow, A. N.: 1941, ‘Die lokale Struktur der Turbulenz in einer inkompressiblen zähen Flüssigkeit bei sehr großen Reynoldsschen Zahlen’, Dokl. Akad. Nauk. SSSR 32, 299–303. Reprint in: H. Goering, 1958: Statistische Theorie der Turbulenz. – Akademie-Verlag, Berlin, pp. 77–81.Google Scholar
  18. Lenschow, D. H. and Stankov, B. B.: 1986, ‘Length Scales in the Convective Boundary Layer’, J. Atmos. Sci. 43, 1198–1209.Google Scholar
  19. Lenschow, D. H., Mann, J., and Kristensen, L.: 1994, ‘How Long Is Long Enough when Measuring Fluxes and Other Turbulence Statistics?’, J. Atmos. Oceanic Tech. 11, 661–6731.Google Scholar
  20. Mahrt, L. and Ek, M.: 1993, ‘Spatial Variability of Turbulent Fluxes and Roughness Lengths in HAPEX-MOBILHY’, Boundary-Layer Meteorol. 65, 381–400.Google Scholar
  21. Mann, J. and Lenschow, D. H.: 1994, ‘Errors in Airborne Flux Measurements’, J. Geophys. Res. D 99, 14,519–14,526.Google Scholar
  22. Mason, P. J.: 1988, ‘Large-Eddy Simulation of the Convective Atmospheric Boundary Layer’, J. Atmos. Sci. 46, 1492–1516.Google Scholar
  23. Mason, P. J.: 1994, ‘Large-Eddy Simulation: A Critical Review of the Technique’, Quart. J. Roy. Meteorol. Soc. 120, 1–26.Google Scholar
  24. Moeng, C.-H. and Wyngaard, J. C.: 1988, ‘Spectral Analysis of Large-Eddy Simulations of the Convective Boundary Layer’, J. Atmos. Sci. 45, 3573–3587.Google Scholar
  25. Muschinski, A.: 1996, ‘A Similarity Theory of Locally Homogeneous and Isotropic Turbulence Generated by a Smagorinsky-type LES’, J. Fluid. Mech. 325, 239–260.Google Scholar
  26. Nieuwstadt, F. T. M. and Brost, R. A.: 1986, ‘The Decay of Convective Turbulence’, J. Atmos. Sci. 43, 532–546.Google Scholar
  27. Price, G. V. and MacPherson, A. K.: 1973, ‘A Numerical Weather Forecasting Method Using Cubic Splines on a Variable Grid’, Mon. Wea. Rev. 12, 1102–1113.Google Scholar
  28. Raasch, S. and Etling, D.: 1991, ‘Numerical Simulation of Rotating Turbulent Thermal Convection’, Beitr. Phys. Atmosph. 64, 185–199.Google Scholar
  29. Raasch, S. and Etling, D.: 1998, ‘Modelling Deep Ocean Convection: Large Eddy Simulation in Comparison with Laboratory Experiments’, J. Phys. Oceanog. 28, 1786–1802.Google Scholar
  30. Scherf, A. and Roth, R.: 1997, ‘Estimates of Area-Averaged Turbulent Energy Fluxes in a Convectively Driven Boundary Layer Using Aircraft Measurements’, Phys. Chem. Earth 21, 399–403.Google Scholar
  31. Schmidt, H. and Schumann, U.: 1989, ‘Coherent Structure of the Convective Boundary Layer Derived from Large-Eddy Simulations’, J. Fluid Mech. 200, 511–562.Google Scholar
  32. Siemer, A.: 1996, Flugphysikalische und meßtechnische Aspekte flugzeuggestützter meteorologischer Messungen turbulenter Flüsse, Berichte des Instituts für Meteorologie und Klimatologie der Universität Hannover, University of Hannover, Germany, 49.Google Scholar
  33. Taylor, G. I.: 1938, ‘The Spectrum of Turbulence’, Proc. Roy. Soc. London, A 164, 476–490.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • M. Schröter
    • 1
  • J. Bange
    • 1
  • S. Raasch
    • 1
  1. 1.Institute for Meteorology and ClimatologyUniversity of HannoverGermany

Personalised recommendations