Problem statement. Solid Earth (SE) is extremely rich in computational challenges, requiring petascale and exascale infrastructures both to address fundamental scientific questions and to anticipate, mitigate, and manage the occurrence of geohazards and their impacts by advancing on, at least, three fronts:
- Capability computing. First of all, on explicitly solving problems that, traditionally, have been parameterised because at present are unaffordable in terms of size of the computational domain, model resolution, complex physical couplings, and huge amounts of data involved (Scientific Grand Challenges,SGC).
- Capacity computing. Second, by introducing a probabilistic framework through a large ensemble of model realisations, which allows high-end data inversion, model data assimilation, and uncertainty quantification (e.g. for physics-based probabilistic hazard assessments). These capacity workloads can range from tightly coupled, as in the case of ensemble-based data assimilation schemes (e.g. Kalman filters), to loosely coupled as in realisations of hazard scenarios.
- Urgent computing. Finally, on solving currently affordable problems but with much less computing time. This aspect is critical in scenarios of early warning and emergency management, where constrains exist in urgency (e.g. faster than real time tsunami simulations).
Overall objectives. ChEESE has 4 general objectives and 15 specific objectives related to scientific, technical, and socio-economic challenges (see Part B for details). First of all, the project is preparing 11 European flagship Community codes for the upcoming Exascale Era in order to address 12 underpinning scientific, technical, and socio-economic Exascale Computational Challenges (ECC) in the areas of computational seismology, magneto-hydrodynamics, physical volcanology, tsunami modelling, geodynamics and glaciar modelling. During the project, codes will be optimised in terms of performance on different types of accelerators, code scalability, deployment, availability on EuroHPC systems following a CI/CD approach, performance portability across current pre-exascale systems and by co-designing with 7 mini-apps, also on hardware architectures emerging from EuroHPC Pilots. Codes and related workflows are combined to implement 9 Pilot Demonstrators (PDs), intended as proofs of concept to address each of the 12 ECCs. The PDs will materialise in 15 Simulation Cases (PCs) representing capability and capacity use cases of particular interest in terms of science, social relevance, or urgency. The capability-oriented use-cases entail also 4 Scientific Grand Challenges (SGC) that will produce relevant EOSC-enabled datasets and prototype services on aspects of geohazards like UC, Early Warning Systems (EWS), forecasts, and hazard assessments. Last, but not least, ChEESE aims at becoming a hub to integrate different actors concerned with different aspects of the SE phenomena. This integration implies domain-specific training, capacity building, dissemination, market analysis for future exploitation of services and, very important, engage with the European Plate Observing System (EPOS) and longer-term mission-like initiatives like the Digital Agenda and Destination Earth.
