The spectral density technique for the determination of CO2 flux over the ocean

T. Iwata, K. Yoshikawa, Y. Higuchi, T. Yamashita, S. Kato, E. Ohtaki

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The spectral density technique is investigated as a basis for measuring turbulent fluxes of CO2 and water vapour over the sea using observations obtained on a well-designed pier of Kyoto University during September 20-22, 2000. By comparing the turbulent fluxes measured by the spectral density technique with those determined by the eddy correlation technique, a set of parameters of the non-dimensional gradient (φ) and Kolmogorov constant (α) was determined. The following parameters are the optimal selection under unstable conditions for the spectral density technique: φc = φq = (1 - 16z/L)-1/2; αc = 0.78 and αq = 0.76 Here, subscripts c and q refer to CO2 and water vapour; z is height and L is the Obukhov stability length. The present results demonstrate that with rugged sonic anemometer-thermometer sensors and computers, the spectral density technique applied over the sea has an accuracy comparable to that of the eddy correlation technique.

Original languageEnglish
Pages (from-to)511-523
Number of pages13
JournalBoundary-Layer Meteorology
Issue number3
Publication statusPublished - Dec 2005


  • Air-sea interaction
  • COflux
  • Eddy correlation technique
  • Spectral density technique
  • Water vapour flux

ASJC Scopus subject areas

  • Atmospheric Science


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