Toward Exascale Climate Modelling: A Python DSL Approach to ICON’s (Icosahedral Non-hydrostatic) Dynamical Core (icon-exclaim v0.2.0)
Abstract. A refactored atmospheric dynamical core of the ICON model implemented in GT4Py, a Python-based domain-specific language designed for performance portability across heterogeneous CPU-GPU architectures, is presented. Integrated within the existing Fortran infrastructure, the GT4Py core achieves throughput slightly exceeding the optimized OpenACC version, reaching up to 213 simulation days per day when using a quarter of CSCS’s ALPS GPUs. A multi-tiered testing strategy has been implemented to ensure numerical correctness and scientific reliability of the model code. Validation has been performed through global aquaplanet and prescribed sea-surface temperature simulations to demonstrate model’s capability to simulate mesoscale and its interaction with the larger-scale at km-scale grid spacing. This work establishes a foundation for architecture-agnostic ICON global climate and weather model, and highlights poor strong scaling as a potential bottleneck in scaling toward exascale performance.
Authors
- Matthieu Leclair (ORCID: https://orcid.org/0000-0003-3461-4871)
- Hannes Vogt
- M. Rothlin
- Mona Bukenberger (ORCID: https://orcid.org/0000-0002-0171-2996)
- Mauro Bianco
- A. Jocksch (ORCID: https://orcid.org/0000-0002-3327-4230)
- Xavier Lapillonne (ORCID: https://orcid.org/0000-0001-6114-4321)
- T. C. Schulthess (ORCID: https://orcid.org/0000-0002-1086-5812)
- Clarissa Kroll
- William Sawyer
- Anurag Dipankar (ORCID: https://orcid.org/0000-0002-1410-4324)
- Giovanni Serafini (ORCID: https://orcid.org/0000-0003-4962-1257)
- Praveen Kumar Pothapakula (ORCID: https://orcid.org/0000-0002-5654-7975)
- Till Ehrengruber
- Daniel Hupp
- Christoph Müller (ORCID: https://orcid.org/0000-0002-9491-3550)
- Carlos Osuna
- Bettina Weber
- Magdalena Luz
- Chia Rui Ong
- Nicoletta Farabullini
- Abishek Gopal
- Samuel Kellerhals
Institutions
- NSF National Center for Atmospheric Research (US)
- Federal Office of Meteorology and Climatology MeteoSwiss (CH)
- ETH Zurich (CH)
- Institute for Biomedical Engineering (CH)
- Supercomputing Systems (Switzerland) (CH)
- Swisscom (Switzerland) (CH)
Publication Details
- Published
- 2025-10-14
- DOI
- https://doi.org/10.5194/egusphere-2025-4808
- Citations
- 3
- Primary Topic
- Geophysics and Gravity Measurements
- Type
- article
- Field-Weighted Citation Impact
- 5.38