Institute of Energy and Climate Research (IEK)

Troposphere (IEK-8)

PL-ExaESM

Pilot Lab Exascale Earth System Modelling

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.