Module M | Modelling
ITMS modelling module (ITMS-M) aims to develop the elements of a data assimilation system that is capable of using information from a variety of data streams, linking the concentration data (Module B) with the surface flux parameterizations (Module Q&S), to provide spatially and temporally resolved information on GHG fluxes within Germany relevant for the development an operational ITMS.
ITMS-M Phase 2 research (ITMS2-M) aims to provide the development steps needed to transition from the demonstrator stage of ITMS (at the end of Phase 1) to a pre-operational system (First Generation ITMS). More gases and emission sectors will be covered, making use of a growing number of observations, especially satellite data and improved bottom-up and inversion modelling approaches. The continued work in ITMS2-M leverages the combined expertise at three different partnering institutions (DWD, MPI-BGC, and KIT-IMKASF), focusing on different topics;
Further development of the CarboScope-Regional inversion system (CSR), for pre-operational GHG estimation at the Max Planck Institute for Biogeochemistry (MPI-BGC), Principal Investigator: Dr. habil. Christoph Gerbig;
The development of ICON-ART inversion for the establishment of a long-term operational GHG data assimilation system at the Deutscher Wetterdienst (DWD), Principal Investigator: Dr. Andrea Kaiser-Weiss;
The development of ICON-Forward Modelling limited-area implementation (ICON-ART-LAM) at the KIT Institute of Meteorology and Climate Research Atmospheric Trace Gases and Remote Sensing (KIT-IMKASF), interfacing with the DWD ICON-ART development, providing for the capability of aerosol and tracer transport in DWD’s NWP model, Principal Investigator: Dr. Roland Ruhnke
The MPI-BGC is responsible for the coordination of ITMS2-M. The work in ITMS2-M across the different partnering institutions is divided into 14 work packages (WP-M.s), namely:
ITMS2-M WP-M.201 | Operational data assimilation system expansion for generalized GHG inversion (DWD)
This work package focuses on developing a modular and flexible system for greenhouse gas (GHG) data assimilation. The system integrates different types of observations and incorporates advanced data-processing capabilities, including uncertainty characterisation, bias correction, and monitoring tools. It supports a range of data assimilation methods for both atmospheric concentration assimilation and GHG flux inversions.
Scientists involved:
Prof. Roland Potthast
ITMS2-M WP-M.202 | Methane emission verification implementation for DWD operations (DWD)
This work package will provide annual methane (CH₄) inversion estimates throughout Phase 2, building on the successful research and development outcomes from ITMS Phase 1 across Modules B, Q&S, and M. During Phase 2, newly developed and successfully tested methods and data products will also be progressively integrated into the ICON-ART-based operational methane inversion system at DWD.
Scientists involved:
Dr. Andrea Kaiser-Weiss
ITMS2-M WP-M.203 | Methane satellite retrieval and FTIR column assimilation with DACE (DWD)
This work package focuses on further developing the DWD Data Assimilation Coding Environment (DACE) to enable the integration of greenhouse gas observations from satellites and ground-based column measurements, such as Fourier-transform infrared (FTIR) spectrometers. The development builds on methods and results established during ITMS-M Phase 1.
Scientists involved:
Dr. Andrea Kaiser-Weiss
ITMS2-M WP-M.204 | Continued research for ICON-ART - CTDAS satellite data assimilation (MPI-BGC)
Building on previous developments within the RiGHGorous project, this work package will further develop the ensemble-based ICON-ART–CTDAS (CarbonTracker Data Assimilation Shell) framework for methane (CH₄) assimilation and its application to satellite observations. Key activities include improving the representation of model–data mismatch and correlated measurement uncertainties, particularly those relevant to satellite remote sensing, and extending the framework to CO₂ assimilation.
Observations from TCCON/COCCON, aircraft, and AirCore will support the evaluation and validation of the system, in collaboration with Module B. In addition, meteorological input fields for STILT will be generated from short-term ICON-ART forecasts, building on developments from ITMS Phase 1.
Scientists involved:
Dr. habil. Christoph Gerbig
ITMS2-M WP-M.205 | CO2 forward modelling with ICON-ART utilizing ITMS prior flux products (DWD)
This work package focuses on improving the representation of the large and highly variable CO₂ fluxes from the terrestrial biosphere, providing an important basis for distinguishing between biogenic and anthropogenic CO₂ sources. Existing biogenic CO₂ flux products will be integrated and evaluated for ICON-ART forward modelling, including further testing of the already implemented Vegetation Photosynthesis and Respiration Model (VPRM) in collaboration with ITMS partners. Where appropriate, anthropogenic and oceanic CO₂ flux products from CAMS and other international providers (e.g., G3W) will also be incorporated.
Scientists involved:
Dr. Andrea Kaiser-Weiss
ITMS2-M WP-M.206 | Preparing operational CO2 data assimilation and inversion separating biogenic and anthropogenic parts (DWD)
This work package focuses on developing and adapting the ITMS-M-DWD data assimilation system for CO₂ inversions. Modelled CO₂ from biogenic, anthropogenic, and oceanic sources will be efficiently compared with observations from Module B, providing the basis for selecting suitable observations for the inversion.
Building on the existing ITMS-M-DWD technical framework, the system will be customised for CO₂ and its specific observing systems, including the development of appropriate error characterisations and parameter settings.
Scientists involved:
Dr. Andrea Kaiser-Weiss
ITMS2-M WP-M.207 | Implementation of a seamless super-simplified chemistry within ICON-ART (KIT IMKASF)
This work package further develops the simplified OH chemistry scheme implemented in ICON-ART during Phase 1, which is used to represent the chemical removal of methane (CH₄) from the atmosphere. To enable its reliable long-term application in ITMS, the scheme will be extended to account for important influences on OH concentrations, particularly changes in temperature and stratospheric ozone.
The developments will improve simulated CH₄ profiles for the assimilation of satellite observations and include an assessment of uncertainties associated with the modelled chemical depletion of methane. Emerging AI-based chemistry approaches will also be evaluated as potential alternatives if suitable solutions become publicly available.
Building on WP-M.7 from ITMS Phase 1, this work package thus continues the development of the simplified OH chemistry scheme to enable its seamless and reliable long-term use within the ITMS modelling framework.
Scientists involved:
Dr. Roland Ruhnke
ITMS2-M WP-M.208 | CarboScope-Regional (CSR) reference inversions (MPI-BGC)
This work package will use the CarboScope-Regional (CSR) inversion system to estimate fluxes of CO₂, CH₄, and N₂O across Europe and at national scales, with a particular focus on Germany. The use of continuous atmospheric observations will enable detailed representation of temporal variations in greenhouse gas fluxes, particularly for CO₂.
Building on Phase 1 developments, the work will further develop methods for incorporating night-time observations and vertical profiles to better constrain gross biogenic CO₂ fluxes. Multi-tracer inversion approaches will also be established to improve the separation of anthropogenic and biospheric flux components and support further improvements in atmospheric transport modelling. The benefits of these developments will be evaluated against the established CSR reference inversion.
Scientists involved:
Dr. habil. Christoph Gerbig
ITMS2-M WP-M.209 | Transport in the grey zone (DWD)
This work package focuses on improving the representation of atmospheric tracer transport over Germany and neighbouring regions by implementing a higher-resolution ICON-ART modelling domain (ICON-D2). The increased resolution will better capture atmospheric processes, complex terrain, and valley dynamics that influence greenhouse gas transport.
Further developments will prepare the system for modelling at 2 km resolution and finer, including improved turbulence and convection schemes for kilometre-scale tracer transport. The work will also investigate how different representations of atmospheric transport perform as model resolution increases and explore improved representation of the lower troposphere and mixed layer within the data assimilation framework.
Scientists involved:
Dr. Linda Schlemmer
ITMS2-M WP-M.210 | Assessment of assimilation of mixing height (MH) (MPI-BGC)
This work package aims to improve atmospheric transport in the ITMS inversion systems by making greater use of mixing-height observations from the European ceilometer network. Building on methods developed in Phase 1, the observational dataset will be expanded with European-scale measurements from the E-PROFILES network, providing more consistent information on planetary boundary layer (PBL) and mixing heights across the modelling domain.
The extended dataset will be incorporated into the STILT–CSR framework, while methods will also be developed to directly integrate observation-based mixing heights into the ICON-ART–CTDAS framework through data assimilation. Different assimilation approaches will be evaluated and tested to determine their impact on atmospheric transport and greenhouse gas simulations. Successful developments will provide the basis for potential integration into the operational system following Phase 2. The work will be closely coordinated with WP-M.209 to ensure consistency in ICON model configurations, parameterisation choices, and model performance evaluation.
Scientists involved:
Dr. habil. Christoph Gerbig
ITMS2-M WP-M.211 | Multi-species inversion using Rn and CH4, Rn + CO2, and Rn + N2O, within CSR, based on improved Rn Maps from Phase 1 (developed within ITMS-M.6) (MPI-BGC)
This work package investigates the potential of radon (Rn) as an additional tracer to improve estimates of CH₄, CO₂, and N₂O fluxes, taking advantage of similarities in how these gases are affected by vertical atmospheric mixing. The approach will also explore whether radon can help make better use of observations outside the afternoon period, which are more challenging to represent in atmospheric transport models and have therefore not typically been used in CSR inversions.
The multi-species inversion approach will first be implemented and evaluated within the CSR system against standard inversions. Based on its performance, the approach is planned to be subsequently transferred to the ICON-ART–CTDAS framework.
Scientists involved:
Dr. habil. Christoph Gerbig
ITMS2-M WP-M.212 | Development of multi-species assimilation with ICON-ART - CTDAS for separation of fossil and biospheric fluxes for CO2 (MPI-BGC)
This work package aims to improve the separation of fossil-fuel and biospheric CO₂ fluxes, which is important for verifying anthropogenic CO₂ emissions and better understanding changes in natural carbon fluxes.
The ICON-ART–CTDAS framework will be extended to incorporate additional tracers that provide information on fossil-fuel CO₂ emissions, including CO, NO₂, O₂/N₂, and ¹⁴C, as well as satellite-based CO and NO₂ observations. The Online Emission Model (OEM) will also be further developed to support joint flux ensembles for multiple tracers, enabling their combined use in the inversion system.
Scientists involved:
Dr. habil. Christoph Gerbig
ITMS2-M WP-M.213 | Preparation of interfacing with global services in G3W context, Influence of global boundary condition (MPI-BGC)
This work package investigates how lateral boundary conditions (LBCs) from global atmospheric models influence regional CO₂ and CH₄ flux estimates within the CSR inversion system. Previous analyses have shown notable differences in regional estimates when different global products are used, making it important to better understand and quantify this source of uncertainty.
The sensitivity of the inversion results to factors such as the observations assimilated in global and regional systems and the meteorological data used in global transport models will be assessed. The work will determine how strongly regional greenhouse gas estimates depend on the global products providing the boundary conditions and improve the characterisation of uncertainties associated with LBCs.
Scientists involved:
Dr. habil. Christoph Gerbig
ITMS2-M WP-M.214 | Developing N2O emission verification with the ICON-ART system (DWD)
This work package focuses on developing the inversion framework for nitrous oxide (N₂O). Due to the high spatial and temporal variability of N₂O sources and sinks, the inversion will require detailed prior flux information from Module Q&S, including information on how emissions vary over time.
The work will further develop methods for representing and adjusting this temporal variability within the inversion system. Sensitivity studies will also assess the appropriate spatial and temporal resolution for producing robust N₂O flux estimates while accounting for variability at finer scales.
Scientists involved:
Dr. Andrea Kaiser-Weiss