High-precision carbon dioxide instrumentation
The facility deploys cavity ring down spectroscopy (CRDS) instruments for the measurement of atmospheric carbon CO2 concentrations. The CRDS instruments provide a stable and precise measurement of the concentrations of the most important greenhouse gases (CO2, methane (CH4) and water vapour) to the parts per billion level with negligible drift.
These measurements have successfully been used with a Bayesian inverse modelling approach to independently improve the identification of CO2 and CH4 sources and sinks as well as to identify potential source locations to independently assess the efficacy of mitigation efforts.
The instrumentation meets the World Meteorological Organisation’s data quality objectives for global atmospheric watch stations and the integrated carbon observation system atmospheric station specifications.
Technical Specifications
Cavity ring down spectroscopy instruments:
- Cape Point - Located at Cape Point Global Atmospheric Watch station and has been in operation since 2014. The instrument measures CO2 and CH4 concentrations in marine and air masses.
- KwaDela/Kwazamokuhle - The instrument is operated by the North-West University to assess the concentration of CO2, CH4 and carbon monoxide as a result of domestic combustion to attribute the contribution of domestic combustion to local air pollution.
- Elandsfontein - The instrument is located in the regional background site of the industrialised region of the Mpumalanga Highveld.
- Lephalale - The instrument is located in the regional background site of the rapidly industrialising Waterberg region.
| Specification | CO2 | CO | CH4 | H20 |
| Atmospheric range | ~400 000 ppb | ~1 500 ppb | ~ 1 800 ppb | ~20 000ppm |
| Precision (5 sec / 5 min/ 60 min) | <50 ppb / 20 ppb / 10 ppb | <15 ppb / 1.5 ppb / 1 ppb | <1ppb / 0.5 ppb / 0.3 ppb | <30 ppm / 5 ppm |
| Max Drift (24 hours / 1 month) | 100ppb / 500ppb | 10ppb / 50 ppb | 1 ppb / 3 ppb | 100 ppm ± 55 of reading |
| Max uncertainty using reference gas (1 hr average, 2 σ) | <50 ppb | <1 ppb | < 0.5ppb | NA |
| Operating range | 0-1000 ppm | 0-5 ppm | 0-20 ppm | 0-7%v H2O |
