CNit Model Calibration and Results

This archive contains the model calibration data and results for CNit (Carbon-Nitrogen Interactions in Terrestrial ecosystems), a coupled carbon-nitrogen cycle model. The CNit model description is avalibale at: Tang, G., Nicholls, Z., Norton, A., Zaehle, S., and Meinshausen, M.: Synthesizing global carbon–nitrogen coupling effects – the MAGICC coupled carbon–nitrogen cycle model v1.0, Geosci. Model Dev., 18, 2193–2230, https://doi.org/10.5194/gmd-18-2193-2025, 2025. Tang, G., Zaehle, S., Nicholls, Z., Norton, A., Ziehn, T., & Meinshausen, M. Understanding the Drivers of Carbon-Nitrogen Cycle Variability in CMIP6 ESMs with MAGICC CNit v2.0: Model and Calibration Updates. ESS Open Archive. June 16, 2025. https://doi.org/10.22541/essoar.175008280.09297369/v1 CNit Python Documentation: https://cnit.readthedocs.io/en/latest/ The CNit model source code is avalibale at: GitHub public repository: https://github.com/gangtang-au/cnit (CNit v2.1 and later) Tang, G., Zaehle, S., Nicholls, Z., Norton, A., Ziehn, T., & Meinshausen, M. (2025). Model Source Code for the MAGICC Coupled Carbon–Nitrogen Cycle Model – CNit. Zenodo. https://doi.org/10.5281/zenodo.15569387 (CNit v2.0) Tang, G., Nicholls, Z., Norton, A., Zaehle, S., & Meinshausen, M. (2025). Model Source Code for "Synthesizing Global Carbon-Nitrogen Coupling Effects – the MAGICC Coupled Carbon-Nitrogen Cycle Model v1.0". Zenodo. https://doi.org/10.5281/zenodo.15686499 (CNit v1.0) Update: 1 Jan 2026 (initial upload) cali_trendy_best_fitting.csv: Parameter values from the CNit v2.1 calibration against the TRENDY-v11 DGVMs. CNit_example_TRENDY_DGVMs_emulation.ipynb: A notebook demonstrating the use of the calibrated parameters and the execution of CNit simulations. TRENDY_cali_forcing.nc and TRENDY_cali_target.nc: Required data files for running the notebook.