Ensuring compatibility of observation data for greenhouse gas concentrations in the atmosphere at Russian monitoring stations

The report presents the results of observations of atmospheric concentration of CO₂ and CH₄ at a number of Roshydromet stations, including those located in the Arctic zone of the Russian Federation. Modern possibilities of ensuring compatibility of observation data and the issue of creating a local national scale of molar fractions of greenhouse gases are discussed. The results of international interlaboratory comparisons on greenhouse gases are presented.

When solving problems on estimation of greenhouse gas (GHG) balance in the atmosphere on the basis of data on GHG concentrations obtained from different stations, it is fundamentally important to ensure compatibility of such data. Thus, within the framework of the World Meteorological Organization's Global Atmosphere Watch Programme (WMO GAW), the network compatibility targets for CO₂ and CH₄ observations are set at 0.1 ppm and 2 ppb, which is about 0.025% and 0.1% of the global average level of CO₂ (~400 ppm) and CH₄ (~2000 ppb) in the atmosphere, respectively. This high level of data compatibility across the GAW network was made possible by the WMO scale, which was created due to the lack of national gas standards capable of providing the necessary level of compatibility. In the Russian Federation only the Voeikov Main Geophysical Observatory (Roshydromet) operates under the WMO GAW programme, while more scientific organizations are involved in GHG monitoring. This situation is largely due to difficulties associated with the purchase and delivery of gas standards from the WMO Central Calibration Laboratory located in Boulder (USA).

Within the framework of implementation of the most important innovation project of state significance ‘Unified National System for Monitoring of Climate Active Substances’ (UNSM CAS) it is planned to increase the number of greenhouse gases atmospheric concentration observations (CO₂, CH₄ and N₂O) and to integrate the monitoring system into the new WMO programme ‘Global Greenhouse Gas Watch’. Since the UNSM CAS is faced with the task of ensuring compatibility of observation data both within the country and globally, the need for WMO standards is increasing.

The problem of dissemination of the WMO scale through national standardization institutes has recently become a global issue. The International Bureau of Weights and Measures and WMO are working on the solution of this issue. In the Russian Federation it is planned to create a local national scale of molar fraction of greenhouse gases comparable to the WMO scale. Such work is planned in D.I. Mendeleev Institute for Metrology (VNIIM) within the framework of improvement of the state primary standard of units of molar fraction, mass fraction and mass concentration of components in gas and gas condensate media GET 154-2019 in terms of expansion (greenhouse gases) and ensuring comparability with the WMO scale at the level of the state primary standard.

The local National scale will be implemented through two sets of primary reference gas mixtures (PRGM) in 40 dm³ pressurised cylinders. Each set will consist of nine PRGM in the range of molar fractions of carbon dioxide from 380 to 800 ppm. Two kits are being manufactured to monitor the long-term stability of the PRGM.

The report discusses the preparation, stability study of PRGM, and comparison with gas mixtures prepared under CCQM K120.