Treffer: Adapting atmospheric chemistry components for efficient GPU accelerators

Atmospheric models demand a lot of computational power, and solving the chemical processes is one of its most computationally intensive components. This work shows how to improve the computational performance of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry (MONARCH), a chemical weather prediction system developed by the Barcelona Supercomputing Center. The model implements the new flexible external package chemistry across multiple phases (CAMP) for the solving of gas- and aerosol-phase chemical processes that allows multiple chemical processes to be solved simultaneously as a single system. We introduce a novel strategy to simultaneously solve multiple instances of a chemical mechanism, represented in the model as grid cells, obtaining a speedup up to 9x using thousands of cells. In addition, we present a GPU strategy for the most time-consuming function of CAMP. The GPU version achieves up to 1.2x speedup compared to CPU. Also, we optimize the memory access in the GPU to increase its speedup up to 1.7x . ; This work was partially supported by funding from the Ministerio de Ciencia, Innovación y Universidades as part of the BROWNING project (RTI2018- 099894-BI00), the CAROL project (MCIN AEI/10.13039/501100011033 under contract PID2020-113614RB-C21), the Generalitat de Catalunya GenCat-DIUiE (GRR) (2017-SGR-313) and the AXA Research Fund through the AXA Chair on Sand and Dust Storms established at BSC. This work has also received funding from ”Future of Computing Center, a Barcelona Supercomputing Center and IBM initiative (2020)”. Matthew Dawson has received funding from the European Union’s Horizon 2020 research and innovation program under Marie Sk lodowska-Curie grant agreement no. 747048. ; Peer Reviewed ; Postprint (author's final draft)