Actions should aim at reconciling national greenhouse gas inventories with relevant assessment and monitoring systems in Europe (in particular EU and Horizon Europe Associated Countries) including observations from a wide range of monitoring networks, in-situ and remote-sensed) at a range of scales by comparing their results. Aerosols and their precursors should also be included in the analysis, as well as other air pollutants where relevant (e.g. co-emitted species).
Special attention should be given to establishing how the use of top-down techniques that can support the verification of national greenhouse gas inventories and other regulated estimates of emissions and removals, in order to improve or supplement the methods/approaches currently used. Ideally case studies in collaboration with one or more national inventory compilers should be organised for this purpose.
Proposals should aim to develop scientifically robust methodologies, building on achievements from previous research activities in order to decrease to acceptable levels uncertainties associated with emission estimates, identify and constrain irreducible differences and improve the attribution of emissions and removals to their sources (in particular the separation of natural versus anthropogenic fluxes). They should also explore and support the development and implementation of top-down approaches for use in national inventories, as recognised in the 2019 Refinement of the IPCC 2006 Guidelines for National Greenhouse Gas Inventories.
The development and improvement of methodologies should also address the need for versatility of applications, including mobile sources, individual point sources, land, management actions etc. relevant to current and potential future reporting and compliance systems. Furthermore, issues such as open data and metadata standards, transfer of information and tools, and replicability of methodologies and tools outside Europe (mainly in developing countries) should also be addressed.
Beneficiaries are encouraged to take advantage of the relevant national and/or European research infrastructures (e.g. ACTRIS, ICOS etc.).