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Abstract:
The N2O Model Inter-Comparison Project (NMIP) aims at understanding and quantifying the budgets of global and regional terrestrial N2O fluxes, environmental controls and uncertainties associated with input data, model structure and parameters.
Nitrous oxide (N2O) is an important greenhouse gas (GHG) and also an ozone-depleting substance that has both natural and anthropogenic sources. Large uncertainty remains on the magnitude and spatiotemporal patterns of N2O fluxes and the key drivers of N2O production in the terrestrial biosphere. Some terrestrial biosphere models have been evolved to account for nitrogen processes and show the capability to simulate N2O emissions from land ecosystems at the global scale, but large discrepancies exist among their estimates primarily due to inconsistent input data sets, simulation protocol, and model structure and parameterization schemes. Based on the consistent model input data and simulation protocol, the global N2O Model Inter-Comparison Project (NMIP) was initialized with ten state-of-the-art terrestrial biosphere models with N cycling included. Specific objectives of NMIP are to: 1) Unravel the major N cycling processes controlling N2O fluxes in each model and identify the uncertainty sources from model structure, input data and parameters; 2) Quantify the magnitude, spatial and temporal patterns of global and regional N2O fluxes from the pre-industrial period (1860) to present, and attribute the relative contributions of multiple environmental factors to N2O dynamics; and 3) Provide a bench-marking estimate of N2O fluxes through synthesizing the multi-model simulation results and existing estimates from ground-based observations, inventories, and statistical and empirical extrapolations. This study provides detailed descriptions for the NMIP protocol, input data, model structure and key parameters, along with preliminary simulation results. The global and regional N2O estimation derived from the NMIP is a key component of the Global N2O Budget activity jointly led by the Global Carbon Project (GCP) and the International Nitrogen Initiative (INI).
