Boundary-Layer Meteorology

, Volume 97, Issue 3, pp 487–511 | Cite as

Correction Of Eddy-Covariance Measurements Incorporating Both Advective Effects And Density Fluxes

  • Kyaw Tha Paw U
  • Dennis D. Baldocchi
  • Tilden P. Meyers
  • Kell B. Wilson


Equations are presented to correct eddy-covariancemeasurements for both fluctuations in density andnon-zero mean advection, induced by convergence ordivergence of flow, and spatial source/sinkinhomogeneity, under steady-state and transientconditions. This correction collapses to theWebb–Pearman–Leuning expression ifthe mean vertical velocity is zero, and formally addsthe Webb–Pearman–Leuning expression to the correctionssuggested by Lee for conditions ofnon-zero vertical velocity and source/sink and meanscalar horizontal homogeneity. The equation requiresmeasurement of the mean vertical gradients of thescalar concentration of interest (air temperature,humidity, CO2) as well as an accurateestimation of the mean vertical velocity, in additionto the vertical eddy covariance of the scalar. Simplemethods for the approximation of sensor tilt andcomplex terrain flow angle are presented, to allowestimation of non-zero mean vertical velocities. Theequations are applied to data from a maize crop and aforest to give examples of when the correction issignificant. In addition, a term for thethermodynamic expansion energy associated with watervapour flux is derived, which implies that the sonictemperature derived sensible heat flux will accuratelyinclude this contribution.

Advection Carbon dioxide Density correction Eddy covariance 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Baldocchi, D. D. and Vogel, C. A.: 1996, 'A Comparative Study of Water Vapor, Energy and CO2 Flux Densities above and below a Temperate Broadleaf and a Boreal Pine Forest', Tree Physiol. 16, 5–16.Google Scholar
  2. Bernstein, A. B.: 1966, 'Examination of Certain Terms Appearing in Reynolds Equations under Unsteady Conditions and their Implications for Micrometeorology', Quart. J. Roy. Meteorol. Soc. 92, 533–542.Google Scholar
  3. Bernstein, A. B.: 1970, 'The Calculation of Turbulent Fluxes in Unsteady Conditions', Quart. J. Roy. Meteorol. Soc. 96, 762.Google Scholar
  4. Brook, R. R.: 1978, 'The Influence of Water Vapor Fluctuations on Turbulent Fluxes', Boundary-Layer Meteorol. 15, 481–487.Google Scholar
  5. Businger, J. A.:1982, 'Equations and Concepts', in F. T. M. Nieuwstadt and H. van Dop (eds.), Atmospheric Turbulence and Air Pollution Modelling, D. Reidel Publishing Co., Dordrecht, pp. 1–33.Google Scholar
  6. Finnigan, J.: 1999, 'A Comment on the Paper by Lee (1998): On Micrometeorological Observations of Surface-Air Exchange over Tall Vegetation', Agric. For. Meteorol. 97, 55–64.Google Scholar
  7. Foken, T. and Wichra, B.: 1996, 'Tools for Quality Assessment of Surface-Based Flux Measurements', Agric. For. Meteorol. 78, 83–105.Google Scholar
  8. Frank, W. M. and Emmitt, G. D.: 1981, 'Computation of Vertical Total Energy Fluxes in a Moist Atmosphere', Boundary-Layer Meteorol. 21, 223–230.Google Scholar
  9. Iribarne, J. V. and Godson, W. L.: 1981, Atmospheric Thermodynamics, Second Edition, D. Reidel Publishing Co., Dordrecht, 259 pp.Google Scholar
  10. Kondo, J. and Sato, T.: 1982, 'The Determination of the von Karman Constant', J. Meteorol. Soc. Japan 60, 461–474.Google Scholar
  11. Kramm, G., Dlugi, R., and Lenschow, D. H.: 1995, 'A Re-Evaluation of the Webb Correction Using Density-Weighted Averages', J. Hydrol. 166, 283–292.Google Scholar
  12. Laubach, J. and Teichmann, U.: 1999, 'Surface Energy Budget Variability: A Case Study over Grass with Special Regard to Minor Inhomogenieties in the Source Area', Theor. Appl. Climatol. 62, 9–24.Google Scholar
  13. Lee, X.: 1998, 'On Micrometeorological Observations of Surface-Air Exchange over Tall Vegetation', Agric. For. Meteorol. 91, 39–50.Google Scholar
  14. Lee, X.: 1999, 'Reply To: A Comment on the Paper by Lee (1998): On Micrometeorological Observations of Surface-Air Exchange over Tall Vegetation', Agric. For. Meteorol. 97, 65–67.Google Scholar
  15. Mahrt, L., Vickers, D., Howell, J., Hojstrup, J., Wilczak, J. M., Edson, J., and Hare, J.: 1996, 'Sea Surface Drag Coefficients in the Riso Air Sea Experiment', J. Geophys.Res. 101(C6), 14,327–14,335.Google Scholar
  16. Meyers, T. P. and Baldocchi, D. D.: 1993, 'Trace Gas Exchange above the Floor of a Deciduous Forest II. SO2 and O3 Deposition', J. Geophys. Res. 98, 12,631–12,638.Google Scholar
  17. Paw U, K. T., Brunet, Y., Collineau, S., Shaw, R. H., Maitani, T., Qiu, J., and Hipps, L.: 1992, 'On Coherent Structures in Turbulence within and above Agricultural Plant Canopies', Agric. For. Meteorol. 61, 55–68.Google Scholar
  18. Reinking, R. F.: 1980, 'The Respective Effects of Water Vapor and Temperature on the Turbulent Fluxes of Sensible and Latent Heat', Boundary-Layer Meteorol. 19, 373–385.Google Scholar
  19. Smith, M. O., Simpson, J. R., and Fritschen, L. J.: 1985, 'Spatial and Temporal Variation of Eddy Flux Measures of Heat and Momentum in the Roughness Sublayer above a 30-m Douglas Fir Forest', in B. A. Hutchison and B. B. Hicks (eds.), The Forest-Atmosphere Interaction, D. Reidel Publishing Co., Dordrecht, pp. 563–581.Google Scholar
  20. Sun, J., Esbensen, S. K., and Mahrt, L.: 1995, 'Estimation of Surface Heat Flux', J. Atmos. Sci. 52, 3162–3171.Google Scholar
  21. Swinbank, W. C.: 1951, Measurement of Vertical Transfer of Heat and Water Vapor by Eddies in the Lower Atmosphere', J. Meteorol. 8, 135–145.Google Scholar
  22. Swinbank, W. C.: 1955, Eddy Transports in the Lower Atmosphere, Tech. Paper No. 2, Division of Meteorological Physics, Commonwealth Scientific and Industrial Research Organization, Melbourne, Australia, 30 pp.Google Scholar
  23. Van Mieghem, J.: 1949, 'Les equations générales de la méchanique et de l'énergétique des milieux turbulents en vue des applications à la météorologie', Mem. l'Inst. Roy. Météorol. Belgique 34, 1–59.Google Scholar
  24. Webb, E. K., Pearman, G. I., and Leuning, R.: 1980, 'Correction of Flux Measurements for Density Effects due to Heat and Water Vapour Transfer', Quart. J. Roy. Meteorol. Soc. 106, 85–100.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Kyaw Tha Paw U
    • 1
  • Dennis D. Baldocchi
    • 2
  • Tilden P. Meyers
    • 3
  • Kell B. Wilson
    • 3
  1. 1.Atmospheric ScienceUniversity of CaliforniaDavisU.S.A.
  2. 2.Department of Environmental Science, Policy and ManagementUniversity of CaliforniaBerkeleyU.S.A.
  3. 3.Atmospheric Turbulence and Diffusion Division, Environmental Research LaboratoryNational Oceanic and Atmospheric AdministrationOak RidgeU.S.A.

Personalised recommendations