[Study on the in-situ measurement of greenhouse gas by an improved FTIR].

The real-time, automatic, highly accurate and efficient system for measuring the mixing ratios of CO2, CH4, CO and N2O has been developed by combining the commercial FTIR system (Wollongong University) with an auto-sampling system and a working standard module. Based on the tests conducted, the FTIR showed the high precision and a relatively low accuracy associated with its poor determination of correction factors. The absolute error of the mixing ratio of CO was above 38.8 x 10(-9), suggesting that FTIR alone could not meet the requirement for the real time measurement. Using the working standard gases to adjust results from the FTIR significantly improved the accuracy of measurements. For both static and dynamic conditions, the discrepancies between the measured results and the real values were below 0.11 x 10(-6), 1.8 x 10(-9), 0.15 x 10(-9) and 0.5 x 10(-9) for CO2, CH4, N2O and CO respectively, meeting the requirements for the atmospheric real-time measurements. During 6 days in-situ measurements of greenhouse gas outside the lab, the precision of target gas can reach 0.05 x 10(-6), 0.2 x 10(-9), 0.07 x 10(-9), 0.5 x 10(-9) for CO2, CH4, N2O, CO, and inaccuracy can be 0.09 x 10(-6), 0.4 x 10(-9), 0.14 x 10(-9), 0.5 x 10(-9), respectively.