Limitations of an eddy-correlation technique for the determination of the carbon dioxide and sensible heat fluxes |
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| Authors: | R L Desjardins E R Lemon |
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| Institution: | 1. Agronomy Dept., Cornell University, Ithaca, N.Y., U.S.A.
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| 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: - 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.
- The deviation from steady-state conditions for 10-min periods was found to have a significant effect on the eddy flux estimates.
- Temperature fluctuations of the air sample passing through the CO2 infrared gas analyzer were found to be non-negligible but could be easily corrected.
- A 1° misalignment of the vertical anemometer affected these eddy fluxes by less than 10% under all circumstances studied.
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