E2.13 E3SM land biogeochemistry modeling

Land biogeochemistry (BGC) dynamically responds to the changing climate and significantly feeds back with climate system via multiple avenues, either positively or negatively. Land BGC thus plays an important role in shaping the future climate. Accurate simulation of land BGC is, however, challenging due to the limited process level understanding of land surface biogeochemistry, model structural uncertainty as well as model parameterization bias. Here, we reported improvements on E3SM land surface biogeochemistry process representation, and demonstrated the improved model fidelity through a comprehensive benchmarking approach using the International Land Model Benchmarking (ILAMB) infrastructure. We showed that offline simulations of major components (fluxes and pools) of land surface Carbon, Water, and Energy cycles have been largely improved, compared with CLM4.5, from which ELM started. We also showed some preliminary results from the Coupled Biogeochemistry (CBGC) simulations (ongoing efforts), and diagnosed potential bias across the land surface for different biogeochemical processes.

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