Publication Type:Book Chapter
Source:Australian Baseline Atmospheric Program 2007-2008, p.7 - 22 (2011)
Accurate baseline measurements of clean air composition are technically demanding, and benefit from advances in instrumentation which improve accuracy and lower the cost and effort of ownership. The University of Wollongong FTIR trace gas analyser for determination of atmospheric trace gas concentrations has been significantly refined in the past decade since its initial development, providing improved accuracy and greater ease of operation. From October 2008 to February 2009 we operated a new analyser at Cape Grim, parallel to the CSIRO LoFlo CO2 analyser and AGAGE automated GC system. The FTIR analyser drew air from the 70-m tower inlet and operated continuously and autonomously for 110 days measuring 10-minute average concentrations of CO2, ∂13C-CO2, CH4, CO and N2O. Here the measurements are compared with LoFlo for CO2, AGAGE for the other gases and isotope ratio mass spectrometry for ∂13C in CO2. The FTIR analyser provided precisions significantly better than those provided by AGAGE for all co-measured species, but less than that of LoFlo for CO2. In March and April 2010 we also operated the same analyser at CSIRO’s Global Atmospheric Sampling Laboratory (GASLAB), making measurements of 36 standard calibration cylinders with well-characterised concentrations. We present the results of this comparison, in which the FTIR shows good precision and linearity over all measured concentration ranges. The FTIR analyser provides a cost-effective, low maintenance solution for the simultaneous measurement of the target species.