Model Source Code for "Synthesizing Global Carbon-Nitrogen Coupling Effects – the MAGICC Coupled Carbon-Nitrogen Cycle Model v1.0"

MAGICC_CN.py is the model source code (Python) for the coupled carbon-nitrogen cycle in MAGICC. 

para_dict_A is a dict of parameters and their values for the calibration. 

MAGICC homepage: https://magicc.org/

Update 18 Jun 2025:

      1. New model version (CNit v2.0) and calibration released:

• CNit v2.0 model description and calibration preprint: 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 v2.0 model source code and calibration: 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

      2. CNit v1.0 model description and calibration paper: 

• 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.

Update 19 Dec 2024:

1. Revised paper title: Synthesizing Global Carbon-Nitrogen Coupling Effects – the MAGICC Coupled Carbon-Nitrogen Cycle Model v1.0
2. Add a para_dict_A.csv in case the .pkl file cannot be opened. 

Update 30 Jan 2025:

1. Add the custom Python modules required for MAGICC_CN.py, including exceptions.py, unit_registry.py, timeseries.py, utils.py, and maths.py.