Refining Simulations of Northern Peatlands via Parameter Optimization and Mechanistic Improvements in the E3SM land Model

Peatlands are vital components of the global carbon cycle, yet their responses to changing environmental conditions remain uncertain. To improve predictions of peatland dynamics, we extended the Energy Exascale Earth System (E3SM) land model (ELM) to simulate peatland ecosystems. This model, ELM-Peatlands, was initially developed for site-level simulations of the SPRUCE (Spruce and Peatland Responses Under Changing Environments) experiment, incorporating detailed representations of peatland hydrology, carbon cycling, and plant functional types (PFTs) specific to these ecosystems. ELM-Peatlands is now calibrated and applied to simulate 12 northern peatland sites using site-specific information and ERA5 reanalysis meteorological data.

With the eventual goal of regional-scale simulation, ELM-Peatlands is being enhanced with calibrated PFT parameters, enabling accurate representation of diverse peatland systems. We evaluate the sensitivity of model outputs to parameters at different sites, enabling selection of the most important parameters to calibrate. Model calibration utilizes site-specific observations to optimize parameters related to vegetation, soil hydrology, and carbon dynamics, ensuring robust performance across varying climatic and ecological conditions. The ERA5 meteorology provides high-resolution, physically consistent forcing data to drive these simulations. Preliminary results demonstrate the model’s capacity to capture site-level variability in carbon and water fluxes while highlighting sensitivities to hydrological and climatic drivers. This work is the first step in the application of ELM-Peatlands at regional and global scales, improving our understanding of peatland feedbacks under future climate scenarios.