Report of the Pilot study CCQM-P188 (in parallel with CCQM-K120.a and b)
Christopher W. Meyer, Flores Edgar, Viallon Joele, Tiphaine Choteau, Philippe Moussay, Faraz Idrees, Robert Wielgosz, Daniel Rzesanke
The Pilot Study CCQM-P188 was conducted in parallel of the Key Comparisons CCQM-K120.a and CCQM-K120.b, which were designed to evaluate the level of compatibility of participants capabilities for value assigning carbon dioxide in air reference gas mixtures in the range (380- 800) μmol/mol. It included two participants which did not take part in the Key Comparisons for the following reasons: The Central Analytical Laboratory (CAL) of ICOS (Integrated Carbon Observation System) participated as an expert guest laboratory. The ICOS-CAL aims to ensure the accuracy of ICOS atmospheric measurement data as well as their traceability to the WMO scale. It provides reference gases for calibration of continuous in-situ measurements performed at monitoring stations, including real air reference gas with a certified value of carbon dioxide in air. It was agreed by the GAWG that its participation in this comparison would be of value to participating NMISs/DIs and bring a second link to the WMO scale as maintained by NOAA, which is itself a participant of the comparison as a designated institute by WMO. The second participant was the BIPM, which took part as a participant with its PVT-CO2 facility, which was still under development at the time of the comparison. It was the occasion for the BIPM to benchmark the performance of its system at its current state of development, based on accurate pressure measurements, using a method similar to that employed by NOAA1. This study involved the simultaneous comparison of a suite of 2 gas standards prepared by ICOS and 3 gas standards value assigned by the BIPM against cylinders prepared by laboratories that took part in the Key Comparison CCQM-K120, using exactly the same protocol.