CAL services

The ICOS Central Analytical Laboratories (CAL) ensure the accuracy of ICOS atmospheric measurements. ICOS Atmosphere Class 1 stations receive a full set of analytical services from the Central Analytical Laboratories, including calibration services (reference gas standardisation) and flask analysis for trace gases, the ratio of oxygen/nitrogen in air and carbon dioxide (CO2) stable isotope and radiocarbon analysis. ICOS Atmosphere Class 2 stations receive basic calibration services.

The CAL consists of the Flask and Calibration Laboratory (FCL) and the Central Radiocarbon Laboratory (CRL).


On this page:

Reference gas standardisation

ICOS has developed a broad range of standardisation protocols to ensure the highest observational standards for each ICOS station. One component of this standardisation is that all the ICOS Atmosphere stations are centrally served with reference gases produced at the FCL as real air gas mixtures. This service is part of the quality assurance and aims to improve the internal measurement consistency in the ICOS Atmosphere station network.

To ensure compatibility of the ICOS atmospheric greenhouse gas observations with data from other global monitoring networks, the measurements need to be traceable to the respective World Meteorological Organization (WMO) calibration scales. Calibration at the FCL is done by using a set of the WMO standards calibrated by the WMO Central Calibration Laboratory.

Flask analysis

Air samples are generally collected at all ICOS Atmosphere Class 1 stations according to the ICOS Flask Sampling Strategy with automated samplers. They are then transferred to the FCL and depending on the goal of the sampling to the CRL for analysis. This procedure provides a high-quality and independent quality control for continuously measured greenhouse gas concentrations of CO2, methane (CH4), nitrous oxide (N2O) and carbon monoxide (CO). The sampling also gives information on components currently not monitored at the stations. Lastly, flask sampling aims to collect samples that are significantly influenced by fossil fuel CO2 (ffCO2) emissions, for the purpose of quantifying the share of fossil fuel sources contributing to atmospheric CO2 by radiocarbon (14CO2) analysis.

Radiocarbon sampling

ICOS follows a two-state radiocarbon sampling strategy to track long-term changes in the human emissions of CO2 from fossil fuels in the atmosphere. The CRL analyses two weekly integrated samples from the ICOS Atmosphere 1 Class stations. The measurements are complemented by spot samples that allow to determine the fossil CO2 content of a specific air mass. CRL is continuously expanding its methods to separate the fossil fuel contribution to CO2 in the atmosphere.

Contact details

Contact CAL for more information on the services for ICOS Atmosphere stations:

Flask and Calibration Laboratory (FCL)

Head of Flask and Calibration Laboratory
Dr Armin Jordan
ICOS - Flask and Calibration Laboratory (FCL)
Technologiecenter am Felsenkeller (TCF) - Eingang C
Kahlaische Str. 4
07745 Jena

contact-fcl (at)
standards (at)
flasks (at)



Central Radiocarbon Laboratory (CRL)

Head of Central Radiocarbon Laboratory
Dr Samuel Hammer
Heidelberg University, Institute of Environmental Physics
ICOS – CRL Karl Otto Münnich 14C Laboratory
Berliner Straße 53
69120 Heidelberg

contact-crl (at)