caa a22 4500 475777166 CHVBK 20180406123634.0 cr unu---uuuuu 170329e20000901xx s 000 0 eng 10.1023/A:1002642028984 doi (NATIONALLICENCE)springer-10.1023/A:1002642028984 Testing of the bandpass eddy covariance method for a long-term measurement of water vapour flux over a forest [Elektronische Daten] [Tsutomu Watanabe, Katsumi Yamanoi, Yukio Yasuda] 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. Kluwer Academic Publishers, 2000 Bandpass covariance nationallicence Eddy correlation nationallicence Frequency response nationallicence Long-term measurement nationallicence Scalar flux nationallicence Water vapour nationallicence Watanabe Tsutomu Forest Environment Division, Forestry and Forest Products Research Institute, Tsukuba, Japan aut Yamanoi Katsumi Tohka-machi Experiment Station, Forestry and Forest Products Research Institute, Tohka-machi, Japan aut Yasuda Yukio Forest Environment Division, Forestry and Forest Products Research Institute, Tsukuba, Japan aut Boundary-Layer Meteorology Kluwer Academic Publishers 96/3(2000-09-01), 473-491 0006-8314 96:3<473 2000 96 10546 https://doi.org/10.1023/A:1002642028984 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1002642028984 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Watanabe Tsutomu Forest Environment Division, Forestry and Forest Products Research Institute, Tsukuba, Japan aut NATIONALLICENCE 700 1- Yamanoi Katsumi Tohka-machi Experiment Station, Forestry and Forest Products Research Institute, Tohka-machi, Japan aut NATIONALLICENCE 700 1- Yasuda Yukio Forest Environment Division, Forestry and Forest Products Research Institute, Tsukuba, Japan aut NATIONALLICENCE 773 0- Boundary-Layer Meteorology Kluwer Academic Publishers 96/3(2000-09-01), 473-491 0006-8314 96:3<473 2000 96 10546 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer