A fast response atmospheric CO2 sensor for eddy correlation flux measurements

The direct measurement of carbon dioxide fluxes in the atmospheric boundary layer is of considerable importance in studies of ocean-atmosphere exchange and in productivity of crops and forests. A promising technique for measuring CO₂ fluxes, the eddy correlation method, requires a sensitive fast response sensor. We describe the sensor requirements and present a design which has proved successful in a preliminary CO₂ flux measurement. The sensor responds to gas concentration fluctuations up to a frequency of 10 Hz with an rms noise corresponding to CO₂ concentration fluctuations of about 0.3 ppm.