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The Earth system models used in nextGEMS, explained

10. May 2024

Typically, Earth system models employ grid spacing of 100 or 150 km to represent processes on land, in the atmosphere, in the oceans and sea-ice, which could result in imprecise climate projections. By using a fifty-fold finer horizontal grid with a 3 km scale – or storm resolving models –, nextGEMS is trying to reach an advanced level of resolution in climate modelling. These types of models can realistically project critical small-scale climate processes that have been neglected or represented empirically through parametrisations before, possibly introducing errors or bringing unclearness to the models.

Hence, nextGEMS is currently simulating the climate at resolutions never seen before with the objective of improving two already existing models: ICON and IFS.

What is ICON?

The ICOsahedral Nonhy-drostatic – also known as ICON – model was developed by the Max Planck Institute for Meteorology and the German Weather Service. Primarily, it was established for the simulation of the components of the Earth system and their interactions at kilometre and sub-kilometre scales on global and regional domains, according to Hohenegger et al. (2023). In other words, a model like ICON has the capacity to substantially represent terrestrial and marine vegetation that grows and dies. For instance: atmospheric chemistry; carbon, nitrogen, sulphur, and phosphorus cycles; and dynamical ice sheets.

An interesting feature of the model is that it has been able to run coupled, simulating the system interactions between the ocean, atmosphere, and land. Furthermore, the study executed by Hohenegger et al. (2023) showed the model can run coupled for one year at uncommon scales: for a few months with a grid spacing of 2.5 km and for a few days with a grid spacing of 1.25 km. In that way, ICON has made it possible to simulate the biogeochemical processes happening both on land and on the ocean, showing its influence on carbon flows.

ICON model
Overview of the ICON Sapphire model configuration. Retrieved from Hohenegger et al. (2023)

What is IFS? 

The Integrated Forecasting System (IFS), developed by the European Centre for Medium-Range Weather Forecasts (ECMWF) is a model used to produce skilful medium-range weather forecasts. In other words, it provides forecasts for a period extending from about three to seven days in advance for the ECMWF Member and Co-operating States. Moreover, the model has opened up the possibility of providing broader environmental services, such as monitoring climate change or forecasting risks that involve floods, air pollution and wildfires (Maskell, 2022). 

For instance, air quality and increasing levels of greenhouse gases in the atmosphere are important concerns. In that sense, IFS is used to produce forecasts of European air quality; information for the solar energy sector; and monitoring of the ozone layer. Taking that into account, through nextGEMS the model can be improved to reproduce encompassed interactions among atmosphere, land, and ocean or sea ice at a high level of detail.

IFS model
Illustration of the ECMWF Earth system approach. Retrieved from Maskell (2022)

In the attempt of improving these models, projects like nextGEMS are aiming to provide a wide range of environmental possibilities and climate knowledge to society. For instance, through the enhancement of ICON and IFS, decisions like where it is possible to install solar panels or where can fisheries take place are likely to be better assessed, ideally reducing hazards and reinforcing benefits.


Hohenegger, C., Korn, P., Linardakis, L., Redler, R., Schnur, R., Adamidis, P., Bao, J., Bastin, S., Behravesh, M., Bergemann, M., Biercamp, J., Bockelmann, H., Brokopf, R., Brüggemann, N., Casaroli, L., Chegini, F., Datseris, G., Esch, M., Geet, G., … Stevens, B. (2023). ICON-Sapphire: simulating the components of the Earth system and their interactions at kilometer and subkilometer scales. Geoscientific Model Development, 16(2), 779-811.

Maskell, K. (2022, April 7). Global numerical modelling at the heart of ECMWF’s forecasts. ECMWF

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