Abstract
Increased usage of the conditional sampling techniques of the relaxed eddy accumulation method of measuring trace gas fluxes from vegetation raises questions as to the physical meaning of the β factor. Using sensible heat flux data to calculate β by comparison of the eddy covariance and conditional sampling algorithms suggests a mean value of 0.56. A theoretical approach based on the Gram-Charlier distribution is shown to need cross product terms up to the 4th order to provide a good description of β by taking into account the skewness and flatness of the distributions of the components of wind velocity and scalars. This description also shows that β is not constant but will vary with turbulence characteristics in time and space. Values of β for scalar and momentum fluxes are shown to vary over a typical range of 0.40 to 0.63.
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Milne, R., Beverland, I.J., Hargreaves, K. et al. VARIATION OF THE β COEFFICIENT IN THE RELAXED EDDY ACCUMULATION METHOD. Boundary-Layer Meteorology 93, 211–225 (1999). https://doi.org/10.1023/A:1002061514948
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DOI: https://doi.org/10.1023/A:1002061514948