Towards efficient high-resolution simulations of dust storm formation over large areas in North Africa using HPC

This study presents the results of scalability tests of the WRF-Chem model on the MareNostrum 5 GPP supercomputing system, aimed at enabling high-resolution simulations of dust storm formation across large regions of North Africa. Simulations were conducted with three nested domains, reaching a 2 km horizontal resolution in the innermost domain. Two large areas of different size were evaluated. For the smaller domain, the optimal wall-clock time was achieved using approximately 2,000 cores, resulting in a simulation-to-wall-clock time ratio of 2:1. However, parallel efficiency declined significantly beyond ~1,200 cores, indicating limited scalability at higher core counts. In contrast, simulations over the larger domain maintained high efficiency between 1,680 and 2,016 cores, even outperforming the 2,500-core configuration in normalized cost. These findings highlight the importance of balancing runtime and resource efficiency. Future work should investigate which components of WRF-Chem dominate computational cost to better exploit HPC resources and guide model optimization