Journal of Atmospheric Chemistry

, Volume 71, Issue 1, pp 79–94 | Cite as

Is the empirical coefficient b for the relaxed eddy accumulation method constant?

  • Ayaka SakabeEmail author
  • Masahito Ueyama
  • Yoshiko Kosugi
  • Ken Hamotani
  • Takashi Hirano
  • Ryuichi Hirata


The relaxed eddy accumulation (REA) method is an attractive alternative to the eddy covariance method to measure trace-gas flux, because it allows the use of analyzers with an optimal integration time to reduce the noise. However, the use of an empirical coefficient b results in uncertainties in the REA method. The consistency of b for temperature was investigated using a 1 year dataset obtained at three forest sites in East Asia: a temperate evergreen coniferous forest, a tropical evergreen broadleaf forest, and a cool-temperate deciduous coniferous forest. The observational b ranged from 0.54 to 0.57 under unstable conditions. Although the values for observational b were within narrow ranges among the sites, there were slight site-specific differences. We introduced new expression of b, similarity b, based on scalar similarity using the integral turbulence characteristics to investigate the nature of b. Both the observational and similarity b increased with increasing atmospheric stability under stable conditions, when lower values for the standard deviation of the vertical wind velocity resulted in higher values for b. The variations in b under stable conditions differed among sites. There were no seasonal variations in the observational b at all sites. Consequently, the present study recommends determining the coefficient b for unstable conditions for each site and considering changes in b associated with atmospheric stability in order to minimize errors in the REA method.


Atmospheric stability Empirical coefficient b Integral turbulence characteristics Relaxed eddy accumulation Trace gas flux 



This work was supported by JSPS KAKENHI Grant Numbers 23248023, 21380095.


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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Ayaka Sakabe
    • 1
    • 5
    Email author
  • Masahito Ueyama
    • 2
  • Yoshiko Kosugi
    • 1
  • Ken Hamotani
    • 2
  • Takashi Hirano
    • 3
  • Ryuichi Hirata
    • 4
  1. 1.Laboratory of Forest Hydrology, Graduate School of AgricultureKyoto UniversityKyotoJapan
  2. 2.Graduate School of Life and Environmental SciencesOsaka Prefecture UniversitySakaiJapan
  3. 3.Research Faculty of AgricultureHokkaido UniversitySapporoJapan
  4. 4.Center for Global Environmental ResearchNational Institute for Environmental StudiesTsukubaJapan
  5. 5.Forest Hydrology LabKyoto UniversityKyotoJapan

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