A parallel implementation of the confined-unconfined aquifer system model for subglacial hydrology: design, verification, and performance analysis (CUAS-MPI v0.1.0)

• Main Authors: Fischler, Yannic, Kleiner, Thomas, Bischof, Christian, Schmiedel, Jeremie, Sayag, Roiy, Emunds, Raban, Oestreich, Lennart Frederik, Humbert, Angelika
• Format: Text
• Language: English
• Published: 2023
• Subjects: Greenland; Ice Sheet
• Online Access: https://doi.org/10.5194/gmd-2022-312; https://gmd.copernicus.org/preprints/gmd-2022-312/

The subglacial hydrological system affects the motion of ice sheets, the ocean circulation by freshwater discharge, as well as marginal lakes and rivers. For modelling this system a porous medium model has been developed, representing a confined-unconfined aquifer system (CUAS) with evolving transmissivity. To allow for realistic simulations, we developed CUAS-MPI, an MPI-parallel C/C++ implementation, which employs the PETSc infrastructure for handling grids and equation systems. We describe the CUAS model and our software design and validate the numerical result of a pumping test using5 analytical solutions. We then investigate the scaling behavior of CUAS-MPI and show, that CUAS-MPI scales up to 3840 MPI processes running a realistic Greenland setup. Our measurements show that CUAS-MPI reaches a throughput comparable to the throughput of ice sheet simulations, e.g. the Ice-sheet and Sea-level System Model (ISSM). Lastly, we discuss opportunities for ice-sheet modelling, future coupling possibilities of CUAS-MPI with other simulations, and consider throughput bottlenecks and limits of further scaling.