Open path CO2 analyser

An open path CO2 analyser is described for measuring CO2 fluxes over crop canopies by the eddy correlation technique. The analyser measures CO2 concentration within 0.3 ppm by volume with a time constant of 0.075 s. The CO2 concentration is determined from a comparison of the absorption of infrared radiation in the 3.7 mu m and 4.3 mu m bands over a 1.5 m path.