Abstract
The bandpass eddy covariance method has been used to measure the turbulent flux of scalar quantities using a slow-responsescalar sensor. The method issimilar in principle to the traditional eddy correlation method but includes the estimation of high-frequency components of the flux on the basis of cospectral similarity in the atmospheric surface layer. In order to investigate the performance of the method, measurements of the water vapour flux over a forest with the bandpass eddy covariance method and the direct eddy correlation method were compared. The flux obtained by the bandpass eddy covariance method agreed with that by the eddy correlation method within ±20% for most cases, in spite of a rather slow sensor-response of the adopted hygrometer. This result supports its relevance to a long-term continuous operation, since a stable, low-maintenance,general-purpose sensor canbe utilized for scalar quantities. Oneweak point of the method isits difficulty in principle to measure the correct flux when the magnitude of the sensible heat flux is very small, because the method uses the sensible heat flux as a standard reference for the prediction of undetectable high-frequency components of the scalar flux. An advanced method is then presented to increase its robustness. In the new method, output signals from a slow-response sensor are corrected using empirical frequency-responsefunctions for the sensor,thereby extending the width of the bandpass frequency region where components of the flux are directly measured (not predicted). The advanced method produced correct fluxes for all cases including the cases of small sensible heat flux. The advanced bandpass eddy covariance method is thus appropriate for along-term measurement of the scalar fluxes.
Similar content being viewed by others
References
Anderson, D. E. and Verma, S. B.: 1985, ‘Turbulence Spectra of CO2, Water Vapor, Temperature and Wind Velocity Fluctuations over a Crop Surface’, Boundary-Layer Meteorol. 33, 1-14.
Aoki, M., Chimura, T., Ishii, K., Kaihotsu, I., Kurauchi, T., Mushiake, K., Nakaegawa, T., Ohte, N., Polsan, P., Semmer, S., Sugita, M., Tanaka, K., Tsukamoto, O. and Yasunari, T.: 1998, ‘Evaluation of Surface Fluxes over a Paddy Field in Tropical Environment: Some Findings from a Preliminary Observation of GAME’, J. Japan Soc. Hydrol. Water Resour. 11, 39-60.
Baldocchi, D., Valentini, R., Running, S., Oechel, W., and Dahlman, R.: 1996, ‘Strategies for Measuring and Modelling Carbon Dioxide and Water Vapor Fluxes over Terrestrial Ecosystems’, Global Change Biol. 2, 159-168.
Grelle, A. and Lindroth, A.: 1996, ‘Eddy-Correlation System for Long-Term Monitoring of Fluxes of Heat, Water Vapor and CO2’, Global Change Biol. 2, 297-307.
Hicks, B. B. and McMillen, R. T.: 1988, ‘On the Measurement of Dry Deposition Using Imperfect Sensors and in Non-Ideal Terrain’, Boundary-Layer Meteorol. 42, 79-94.
Högström, U., Bergström, H., Smedman, A.-S., Halldin, S., and Lindroth, A.: 1989, ‘Turbulent Exchange above a Pine Forest, I: Fluxes and Gradients’, Boundary-Layer Meteorol. 49, 197-217.
Horst, T. W. and Oncley, S. P.: 1995, ‘Flux-PAM Measurement of Scalar Fluxes Using Cospectral Similarity’, in Proc. 9th Symp. on Meteorological Observations and Instrumentation, pp. 495-500.
Leuning, R. and Judd, M. J.: 1996, ‘The Relative Merits of Open-and Closed-Path Analyzers for Measurement of Eddy Fluxes’, Global Change Biol. 2, 241-253.
Ohtaki, E.: 1985, ‘On the Similarity in Atmospheric Fluctuations of Carbon Dioxide, Water Vapor and Temperature over Vegetated Fields’, Boundary-Layer Meteorol. 32, 25-37.
Verma, S. B., Ullman, F. G., Billesbach, D., Clement, R. J., Kim, J., and Verry, E. S.: 1992, ‘Eddy Correlation Measurements of Methane Flux in a Northern Peatland Ecosystem’, Boundary-Layer Meteorol. 58, 289-304.
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.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Watanabe, T., Yamanoi, K. & Yasuda, Y. Testing of the bandpass eddy covariance method for a long-term measurement of water vapour flux over a forest. Boundary-Layer Meteorology 96, 473–491 (2000). https://doi.org/10.1023/A:1002642028984
Issue Date:
DOI: https://doi.org/10.1023/A:1002642028984