Articles | Volume 18, issue 22
https://doi.org/10.5194/gmd-18-9167-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-18-9167-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Methods for assessment of models
| 
27 Nov 2025
Methods for assessment of models |
| 27 Nov 2025
| 27 Nov 2025
Quantifying coupling errors in atmosphere-ocean-sea ice models: A study of iterative and non-iterative approaches in the EC-Earth AOSCM
Valentina Schüller
CORRESPONDING AUTHOR
Lund University, Lund, Sweden
Florian Lemarié
Univ. Grenoble Alpes, Inria, CNRS, Grenoble INP, LJK, Grenoble, France
Philipp Birken
Lund University, Lund, Sweden
Eric Blayo
Univ. Grenoble Alpes, Inria, CNRS, Grenoble INP, LJK, Grenoble, France
Related authors
Keerthi Gaddameedi, François Hamon, Dominik Huber, Thibaut Lunet, Pedro S. Peixoto, João Guilherme Caldas Steinstraesser, Martin Schreiber, and Valentina Schüller
EGUsphere, https://doi.org/10.5194/egusphere-2025-5156, https://doi.org/10.5194/egusphere-2025-5156, 2025
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
Short summary
Short summary
We present the open-source software SWEET, with core written in C++, dedicated to the numerical simulation of global spectral methods for the rotating shallow water equations on the biperiodic plane and on the sphere. SWEET is designed to provide a fast and efficient environment for research around time integration methods relevant to atmospheric circulation models. The software offers a versatile implementation that allows users to easily set up and run custom time-stepping schemes.
Keerthi Gaddameedi, François Hamon, Dominik Huber, Thibaut Lunet, Pedro S. Peixoto, João Guilherme Caldas Steinstraesser, Martin Schreiber, and Valentina Schüller
EGUsphere, https://doi.org/10.5194/egusphere-2025-5156, https://doi.org/10.5194/egusphere-2025-5156, 2025
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
Short summary
Short summary
We present the open-source software SWEET, with core written in C++, dedicated to the numerical simulation of global spectral methods for the rotating shallow water equations on the biperiodic plane and on the sphere. SWEET is designed to provide a fast and efficient environment for research around time integration methods relevant to atmospheric circulation models. The software offers a versatile implementation that allows users to easily set up and run custom time-stepping schemes.
Nicholas K.-R. Kevlahan and Florian Lemarié
Geosci. Model Dev., 15, 6521–6539, https://doi.org/10.5194/gmd-15-6521-2022, https://doi.org/10.5194/gmd-15-6521-2022, 2022
Short summary
Short summary
WAVETRISK-2.1 is an innovative climate model for the world's oceans. It uses state-of-the-art techniques to change the model's resolution locally, from O(100 km) to O(5 km), as the ocean changes. This dynamic adaptivity makes optimal use of available supercomputer resources, and allows two-dimensional global scales and three-dimensional submesoscales to be captured in the same simulation. WAVETRISK-2.1 is designed to be coupled its companion global atmosphere model, WAVETRISK-1.x.
Achim Wirth and Florian Lemarié
Earth Syst. Dynam., 12, 689–708, https://doi.org/10.5194/esd-12-689-2021, https://doi.org/10.5194/esd-12-689-2021, 2021
Short summary
Short summary
We show that modern concepts of non-equilibrium statistical mechanics can be applied to large-scale environmental fluid dynamics, where fluctuations are not thermal but come from turbulence. The work theorems developed by Jarzynski and Crooks are applied to air–sea interaction. Rather than looking at the average values of thermodynamic variables, their probability density functions are considered, which allows us to replace the inequalities of equilibrium statistical mechanics with equalities.
Olivier Marti, Sébastien Nguyen, Pascale Braconnot, Sophie Valcke, Florian Lemarié, and Eric Blayo
Geosci. Model Dev., 14, 2959–2975, https://doi.org/10.5194/gmd-14-2959-2021, https://doi.org/10.5194/gmd-14-2959-2021, 2021
Short summary
Short summary
State-of-the-art Earth system models, like the ones used in CMIP6, suffer from temporal inconsistencies at the ocean–atmosphere interface. In this study, a mathematically consistent iterative Schwarz method is used as a reference. Its tremendous computational cost makes it unusable for production runs, but it allows us to evaluate the error made when using legacy coupling schemes. The impact on the climate at longer timescales of days to decades is not evaluated.
Florian Lemarié, Guillaume Samson, Jean-Luc Redelsperger, Hervé Giordani, Théo Brivoal, and Gurvan Madec
Geosci. Model Dev., 14, 543–572, https://doi.org/10.5194/gmd-14-543-2021, https://doi.org/10.5194/gmd-14-543-2021, 2021
Short summary
Short summary
A simplified model of the atmospheric boundary layer (ABL) of intermediate complexity between a bulk parameterization and a full three-dimensional atmospheric model has been developed and integrated to the NEMO ocean model.
An objective in the derivation of such a simplified model is to reach an apt representation of ocean-only numerical simulations of some of the key processes associated with air–sea interactions at the characteristic scales of the oceanic mesoscale.
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Short summary
Earth system models consist of many components, coupled in time and space. Standard coupling algorithms introduce a numerical error, which one can compute with iterative coupling methods. We use such a method for a coupled model of a single vertical column of the atmosphere, ocean, and sea ice. We find that coupling errors in the atmosphere and at the ice surface can be substantial and that discontinuous physics parameterizations lead to convergence issues of the iteration.
Earth system models consist of many components, coupled in time and space. Standard coupling...
