A true eddy accumulation system for trace gas fluxes using disjunct eddy sampling method

A new true eddy accumulation flux measurement system, based on the disjunct sampling approach, has been developed and tested. In disjunct sampling, sh ort, separate samples are taken instead of continuously sampling the air as in traditional relaxed eddy accumulation and eddy covariance systems. This method reduces the number of samples but allows more time to process them. Simulation shows that the fluxes, calculated using disjunct data, are clos e to those calculated using continuous data. The disjunct true eddy accumul ation instrument was successfully deployed to measure monoterpene fluxes at Niwot Ridge, Colorado. The ability of the system to measure the sample flo w accurately critical for any eddy accumulation system, was tested using at mospheric CFC-113 as a tracer, with good results. The system was capable of measuring relatively low alpha -pinene fluxes, below 10 ng m(-2) s(-1) at T = 8 degreesC, over a subalpine forest.