Abstract
An eddy covariance system using a closed-path CO2analyser was constructed for long-term CO2flux measurements above a forest, and its total frequency response was valuated experimentally. The amplitude and phase responses of the system wereexamined through a preliminary test, in which a prescribed pattern of CO2fluctuation was input to the system. The result showed that the amplitude of the output from the system was attenuated as frequency increased, with a half-power frequency of 0.3 Hz. The phase was delayed by the air sampling through a long tube, but the delay in phase decreased asfrequency increased. We then presented a new technique for the correction of flux loss due to the inadequate system response for the eddy covariance measurements of CO2 flux. Using the present system and the correction technique, diurnal variations in CO2 flux were measured over a temperate deciduous forest on three days in 1997. The results were compared with the CO2fluxes measured with a fast response open-path gas analyser. The CO2fluxes from the closed-path system agreed with those from the open-path system after the Webb, Pearman and Leuning correction was made for the latter. In the present test over a forest, the contribution of the frequency-response correction to the CO2fluxes was small and its averaged percentage was only 3%in the daytime. However, the percentage would likely increase, if the system were applied to a shorter vegetation site where high frequency components are more important. The comparison confirmed that we can obtain correct measurements of CO2flux using the present closed-path system and the correction technique.
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Fan, S.-M., Wofsy, S. C., Bakwin, P. S., and Jacob, D. J.: 1990, ‘Atmosphere-Biosphere Exchange of CO2 and O3 in the Central Amazon Forest’ J. Geophys. Res. 95(D-10), 16851-16864.
Goulden, M. L., Munger, J. W., Fan, S.-M., Daube, B. C., and Wofsy, S. C.: 1996, ‘Measurements of Carbon Sequestration by Long-Term Eddy Covariance: Methods and a Critical Evaluation of Accuracy’ Global Change Biol. 2, 169-182.
Högström, U., Bergström, H., Smedman, A.-S., and Halldin, S.: 1989, ‘Turbulent Exchange above a Pine Forest. 1: Fluxes and Gradients’ Boundary-Layer Meteorol. 49, 197-217.
Horst, T.W.: 2000, ‘On Frequency Response Corrections for Eddy Covariance Flux Measurements’ Boundary-Layer Meteorol. 94, 517-520.
Horst, T. W. and Oncley, S. P.: 1995, ‘FLUX-PAM Measurement of Scalar Fluxes Using Cospectral Similarity’ in Proceedings of the 9th AMS Symposium on Meteorological Observations and Instrumentation, pp. 495-500.
Lee, X., Black, T. A., den Hartog, G., Neumann, H. H., Nesic, Z., and Olejnik, J.: 1996, ‘Carbon Dioxide Exchange and Nocturnal Processes over a Mixed Deciduous Forest’ Boundary-Layer Meteorol. 81, 13-29.
Lenschow, D. H. and Raupach,M. R.: 1991, ‘The Attenuation of Fluctuations in Scalar Concentration through Sampling Tubes’ J. Geophys. Res. 96(D-8), 15259-15268.
Leuning, R. and Judd, M. J.: 1996, ‘The Relative Merits of Open-and Closed-Path Analysers for Measurement of Eddy Fluxes’ Global Change Biol. 2, 241-253.
Leuning, R. and King, K. M.: 1992, ‘Comparison of Eddy-Covariance Measurements of CO2 Fluxes by Open-and Closed-Path CO2 Analysers’ Boundary-Layer Meteorol. 59, 297-311.
Leuning, R. and Moncrieff, J.: 1990, ‘Eddy-Covariance CO2 Flux Measurements Using Open-and Closed-Path CO2 Analysers: Correction for Analyser Water Vapour Sensitivity and Damping of Fluctuations in Air Sampling Tubes’ Boundary-Layer Meteorol. 53, 63-76.
Malhi, Y., Nobre, A. D., Grace, J., Kruijt, B., Pereira M. G. P, Culf, A., and Scott, S.: 1998, ‘Carbon Dioxide Transfer over a Central Amazonian Rain Forest’ J. Geophys. Res. 130(D-24), 31593-31612.
McMillen, R. T.: 1988, ‘An Eddy Correlation Technique with Extended Applicability to Non-Simple Terrain’ Boundary-Layer Meteorol. 43, 231-245.
Moncrieff, J. B., Massheder, J. M, de Bruin, H., Elbers, J., Friborg, T., Heusinkveld, B., Kabat, P., Scott, S., Soegaard, H., and Verhoef, A.: 1997, ‘A System to Measure Surface Fluxes of Momentum, Sensible Heat, Water Vapour and Carbon Dioxide’ J. Hydrol. 188/189, 589-611.
Moore, C. J.: 1986, ‘Frequency Response Corrections for Eddy Correlation Systems’ Boundary-Layer Meteorol. 37, 17-35.
Ohtaki, E.: 1982, ‘Infrared Device for Simultaneous Measurement of Fluctuations of Atmospheric Carbon Dioxide and Water Vapour’ Boundary-Layer Meteorol. 24, 109-119.
Philip, J. R.: 1963, ‘The Theory of Dispersal during Laminar Flow in Tubes II’ Aust. J. Phys. 16, 300-310.
Shurpali, N. J., Verma, S., Kim, J., and Arkebauer, T. J.: 1995, ‘Carbon Dioxide Exchange in a Peatland Ecosystem’ J. Geophys. Res. 100(D-7), 14316-14326.
Suyker, A. E. and Verma, S. B.: 1993, ‘Eddy CorrelationMeasurements of CO2 Flux Using a Closed-Path Sensor: Theory and Field Test against an Open-Path Sensor’ Boundary-Layer Meteorol. 64, 391-407.
Valentini, R., De Angelis, P., Matteucci, G., Monaco, R., Dore, S., and Scarascia-Mugnozza, G. E.: 1996, ‘Seasonal Net Carbon Dioxide Exchange of a Beech Forest with the Atmosphere’ Global Change Biol. 2, 199-207.
Watanabe, T., Yamanoi, K., and Yasuda, Y.: 2000, ‘Testing of the Bandpass Eddy Covariance Method for a Long-Term Measurement of Water Vapour Flux over a Forest’ Boundary-Layer Meteorol. 96, 473-491.
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.
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Yasuda, Y., Watanabe, T. Comparative Measurements Of Co2flux Over A Forest Using Closed-Path And Open-Path Co2analysers. Boundary-Layer Meteorology 100, 191–208 (2001). https://doi.org/10.1023/A:1019277003979
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DOI: https://doi.org/10.1023/A:1019277003979