Computing the Full Earth System at 1km Resolution
Daniel Klocke, Claudia Frauen, Jan Frederik Engels, Dmitry Alexeev, René Redler, Reiner Schnur, Helmuth Haak, Luis Kornblueh, Nils Brüggemann, Fatemeh Chegini, Manoel Römmer, Lars Hoffmann, Sabine Grießbach, Mathis Bode, Jonathan Coles, Miguel Gila, William H. Sawyer, Alexandru Calotoiu, Yakup Budanaz, Pratyai Mazumder, Marcin Copik, Brandon Weber, Andreas Herten, Hendryk Bockelmann, Torsten Hoefler, Cathy Hohenegger, Björn Stevens
Abstract
We present the first-ever global simulation of the full Earth system at 1.25 km grid spacing, achieving highest time compression with an unseen number of degrees of freedom. Our model captures the flow of energy, water, and carbon through key components of the Earth system: atmosphere, ocean, and land. To achieve this landmark simulation, we harness the power of 8192 GPUs on Alps and 20480 GPUs on JUPITER, two of the world’s largest GH200 superchip installations. We use both the Grace CPUs and Hopper GPUs by carefully balancing Earth’s components in a heterogeneous setup and optimizing acceleration techniques available in ICON’s codebase. We show how separation of concerns can reduce the code complexity by half while increasing performance and portability. Our achieved time compression of 145.7 simulated days per day enables long studies including full interactions in the Earth system and even outperforms earlier atmosphere-only simulations at a similar resolution.