Greenhouse gases such as Carbon dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O), Sulfur Hexaflouride (SF6) and trace gas Carbon Monoxide (CO) influence climate change leading to global warming. Continuous measurements at World Meteorology Organization/Global Atmospheric Watch (WMO/GAW) monitoring stations are made to determine the amount, trend and possible sources of greenhouse gases are conducted worldwide at background level. To accurately determine the exact mole fraction in the atmosphere, stable and accurate greenhouse gas standards are required. In South Africa (SA), the WMO/GAW Cape Point has long term data of greenhouse gases at background level which is traceable to the calibration scales maintained by the Central Calibration Laboratory (CCL) National Oceanic Atmospheric Administration (NOAA). Due to the high maintenance of the reference standards, shipment of the calibration scales from NOAA to SA is of high cost. As an initiative through collaboration with WMO/GAW Cape Point, the NMISA Gas Analysis Section aims to develop greenhouse gas standards with low uncertainties by gravimetric method and aims to meet the WMO recommended data quality objective for monitoring of background air in the Southern Hemispheres. As described in ISO 6142, the impurities of the trace gas of interest in the high pure gases used to prepare the gravimetric standards will be checked since it’s the most critical contributors to the uncertainty of the final mixture composition prepared by gravimetric method. In this work, the progress of developing greenhouse gas standards will be presented.
Silindile Lushozi is a PhD Student in the Gas Analysis Section researching on greenhouse gases at ambient and emission level. She is developing PRGMs and uses analytical instruments such as CRDS, NDIR, GC-FID/μECD/PDHID for analysis. This work will ensure that the ambient air community complies with the regulation using PRGMs to accurately report about the status of ambient air in South Africa.