Pilot Lab Exascale Earth System Modelling - PL-ExaESM

The Pilot Lab Exascale Earth System Modelling (PL-ExaESM) explores specific concepts to enable exascale readiness of Earth System models and associated work flows in Earth System science.

Earth system models simulate the Earth’s climate including physical and biogeochemical processes and they are important tools for assessing the magnitude and impacts of future climate change. Such models have to run in ever finer resolutions in order to capture extreme events, which, in turn, are often responsible for the majority of weather-related and other environmental impacts. We foresee that next-generation Earth system models will run at resolutions of 1-3 km, which means that around 200 numerical equations must be solved in each of about 100 billion model grid boxes at each model time step (i.e. every minute). With such simulations local scale phenomena can be accurately reproduced and extreme events will be simulated much more accurately than at present. Therefore, these models require ever increasing computer power. The next generation of models is expected to only run on supercomputers with at least 1018 floating point operations per second, i.e. exascale systems. Supercomputer technology is undergoing rapid and fundamental changes: since a few years, processor development has reached physical size limits, and therefore new paradigms for computing processors have to be found. Typically, next-generation processors combine many thousand cores in one processing unit. To use such devices efficiently, new programming concepts must be developed and implemented into Earth system models. Furthermore, these models generate huge amounts of data, and storage technology is also evolving. This implies that new ways for handling Earth system model output and new modelling workflows have to be developed. To enable such gigantic simulations on such gigantic machines necessitates a close collaboration between Earth system modellers and computer scientists. The PilotLab ExaESM offers a platform where these two communities can meet and interact to build the next-generation Earth system models.

In the PL-ExaESM, scientists from 9 Helmholtz institutions work together to address 5 specific problems of exascale Earth system modelling:

  • Scalability: models are being ported to next-generation GPU processor technology and the codes are modularized so that computer scientists can better help to optimize the models on new hardware (Topic 1)
  • Load balancing: asynchronous workflows are being developed to allow for more efficient orchestration of the increasing model output while preserving the necessary flexibility to control the simulation output according to the scientific needs (Topic 2)
  • Data staging: new emerging dense memory technologies allow new ways of optimizing I/O operations of data-intensive applications running on HPC clusters and future Exascale systems (Topic 3)
  • System design: the results of dedicated performance tests of Earth system models and Earth system data workflows are analysed in light of potential improvements of the future exascale supercomputer system design (Topic 4)
  • Machine learning: modern machine learning approaches are tested for their suitability to replace computationally expensive model calculations and speed up the model simulations or make better use of available observation data (Topic 5)

The ESM Pills, a poster series developed by the communication & outreach officers at AWI, aim to deliver simple explanations for various ESM-relevant topics. Scientists from all kind of disciplines, as well as students and everybody else who is interested in modelling in general, can inform themselves about what is going on in the world of modelers.

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On the 25 and 26 of March 2021 JSC is holding the ESM User Forum online training course. The event will take place on two half days, it will start at 14:00 CET on the 25th and will end at 12:30 CET on the 26th, and will include presentations, feedback sessions and a hands-on session (a full agenda can be found here).

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On November 26th and 27th, 2020 the annual meeting of the Pilot Lab ExaESM took place. The project progress of the past months of each topic was discussed. The meeting was splitted in plenary sessions to inform the project members about the current status and in breakout groups of the individual topics to plan the next steps. Additionally talks by Panos Adamidis about the I/O strategies in the ICON model and by Estela Suarez about the „SEA“ projects were given.