greenhouse gases - TITLE

Standards to underpin atmospheric monitoring

Following the CCQM, CCQM Working Group on Gas Analysis (GAWG) and CCQM Working Group on Isotope ratios (IRWG) strategies, the BIPM Chemistry Department coordinates comparisons of National Metrology Institute (NMI) gas standard capabilities for the three major greenhouse gases – carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) – in air, as well as isotope ratios of CO2 relevant to source apportionment and the basis of international scales for carbon isotope. The BIPM maintains specialized facilities to run the comparisons, based on procedures using two different analytical techniques to ensure any method bias is detected, and methods operated at optimized minimum uncertainties.


greenhouse gases - CO2

Ongoing comparisons for CO2

The BIPM has been establishing a central facility to act a stable reference in the future ongoing BIPM.QM−K2 comparison, to compare consistency of amount fraction values in CO2 in air standard mixtures from the participants. This facility is based on the manometric method. It provides SI traceable values of CO2 in air amount fractions by measuring the pressure and temperature of a sample of the standard mixture and of the CO2 extracted from it by cryogeny, completed by the ratio between their volumes. The comparison start date is January 2024.

A second ongoing key comparison, BIPMQM-K5, will be launched soon, to underpin most stringent measurements of background CO2 which require traceability to a common set of standards, referred to as a CO2 scale. The BIPM has been setting up its own scales and is working with the CCQM-GAWG-TG-GHG to develop the protocol of this comparison. The aim is to demonstrate the maintenance or divergence of the relationship between scales based on different sets of primary CO2 in air standards over decadal time periods.

Publications - TITLE


see chemistry publications

see also OZONE

See also