Received: 13 Mar 2018 – Discussion started: 28 Mar 2018
Abstract. The contributions of long-lived nitrous oxide (N2O) to the global climate and environment have received increasing attention. Especially, atmospheric nitrogen (N) deposition has substantially increased in recent decades due to extensive use of fossil fuels in industry, which strongly stimulates the N2O emissions of the terrestrial ecosystem. Several models have been developed to simulate N2O emission, but there are still large differences in their N2O emission simulations and responses to atmospheric deposition over global or regional scales. Using observations from N addition experiments in a subtropical forest, this study compared six widely-used N2O models (i.e. DayCENT, DLEM, DNDC, DyN, NOE, and NGAS) to investigate their performances for reproducing N2O emission, and especially the impacts of two types of N additions (i.e. ammonium and nitrate: NH4+ and NO3−, respectively) and two levels (low and high) on N2O emission. In general, the six models reproduced the seasonal variations of N2O emission, but failed to reproduce relatively larger N2O emissions due to NH4+ compared to NO3− additions. Few models indicated larger N2O emission under high N addition levels for both NH4+ and NO3−. Moreover, there were substantial model differences for simulating the ratios of N2O emission from nitrification and denitrification processes due to disagreements in model structures and algorithms. This analysis highlights the need to improve representation of N2O production and diffusion, and the control of soil water-filled pore space on these processes in order to simulate the impacts of N deposition on N2O emission.
How to cite. Zhang, Y., Ma, M., Fang, H., Qin, D., Cheng, S., and Yuan, W.: Impacts of Nitrogen Addition on Nitrous Oxide Emission: Model-Data Comparison, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2018-126, in review, 2018.
The study aims to examine the performance of six widely–used N2O models under different levels of atmospheric N deposition in a subtropical forest receiving the highest N deposition. The performances are determined by the model structures and algorithms. The study highlights the need to improve representation of N2O production and diffusion processes, and the key control of soil water-filled pore. The results have significant implications for the improvement and future development of N2O model.
The study aims to examine the performance of six widely–used N2O models under different levels...