Preprint presents ITMS demonstrator for estimating German methane emissions

June 16, 2025

As part of the ITMS project, an estimate of German methane emissions for 2021 based on observational data has been published for scientific discussion. The system developed at Deutscher Wetterdienst (DWD) serves as a demonstrator for ITMS.

The Integrated Greenhouse Gas Monitoring System for Germany (ITMS) aims to determine greenhouse gas emissions using observations. In the future, this emission verification is planned to be operated by the DWD which is Germany's National Meteorological Service. A description of a demonstrator for this application, authored by V. Bruch et al., is now available as a preprint for discussion in the scientific community.

The first version of the ITMS demonstrator considers methane emissions in 2021 by simulating the transport of methane in the atmosphere using the ICON-ART numerical weather forecast model. Assumptions on past methane emissions are based on emission data from the Federal Environment Agency “Umweltbundesamt” and the Thünen Institute as well as data from the Copernicus Atmospheric Monitoring Service (CAMS). The comparison of the ICON-ART simulation with atmospheric observations, in particular from the Integrated Carbon Observation System (ICOS) network, allows conclusion on actual emissions.

In Germany, there is a notable difference between the model and observations. One possible explanation for this could be higher emissions in agriculture, for example. Sensitivity tests and independent observational data confirmed the robustness of the results, while synthetic experiments proved the capability to distinguish between emission sectors. The influence of transport uncertainty was also estimated using a meteorological ensemble. Nevertheless, further uncertainties remain, which are now being addressed in the further development of the demonstrator. Altogether, the publication demonstrates that the close connection of the presented system to the operational weather forecast at DWD, its modular design and the use of observation data create the basis for long-term operational and sector-specific, independent emission estimates.

Figure: (a) Spatial distribution of a priori emissions and (b) their relative uncertainties, as well as (c) scaling of emissions by the emissions estimate and (d) absolute uncertainty of this scaling. Source: Bruch et al. 2025.

Figure: (a) Spatial distribution of a priori emissions and (b) their relative uncertainties, as well as (c) scaling of emissions by the emissions estimate and (d) absolute uncertainty of this scaling. Source: Bruch et al. 2025.

The presented research work was funded by BMFRT (Grant 01LK2102B and 01LK2104A) and BMDV.

Reference of the research paper:

Bruch, V., Rösch, T., Jiménez de la Cuesta Otero, D., Ellerhoff, B., Mamtimin, B., Becker, N., Blechschmidt, A.-M., Förstner, J., and Kaiser-Weiss, A. K.: German methane fluxes in 2021 estimated with an ensemble-enhanced scaling inversion based on the ICON–ART model, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-1464, 2025.