Abstract
A modified infrared CO2 gas analyzer, a small thermocouple assembly, a heated-thermocouple anemometer for horizontal wind, and a propeller-type vertical wind sensor were used to measure the eddy fluxes of heat and CO2 above a corn crop. Experimental results of these fluxes are discussed. The main sources of errors of the eddy fluxes using these instruments were estimated:
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(1)
Sensors with a time constant of 0.5 s appear to be fast enough to detect most of the vertical CO2 transfer as long as the sensors are located at least one meter above the crop surface.
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(2)
The deviation from steady-state conditions for 10-min periods was found to have a significant effect on the eddy flux estimates.
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(3)
Temperature fluctuations of the air sample passing through the CO2 infrared gas analyzer were found to be non-negligible but could be easily corrected.
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(4)
A 1° misalignment of the vertical anemometer affected these eddy fluxes by less than 10% under all circumstances studied.
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Contribution from Northeast Region, Soil, Water and Air Sciences, ARS, U.S. Dept. of Agriculture in cooperation with New York State Agricultural Experimental Station at Cornell University, Agronomy Series Paper 1012; P.R.I. Contribution 956.
Agrometeorology Section, Plant Research Institute, Canada Dept. of Agriculture, Ottawa, Ontario KIA OC6 and Agronomy Department, Cornell University, Ithaca, N.Y., 14850, U.S.A.
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Desjardins, R.L., Lemon, E.R. Limitations of an eddy-correlation technique for the determination of the carbon dioxide and sensible heat fluxes. Boundary-Layer Meteorol 5, 475–488 (1974). https://doi.org/10.1007/BF00123493
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DOI: https://doi.org/10.1007/BF00123493