Using the DeNitrification-DeComposition Framework to Simulate Global Soil Nitrous Oxide Emissions in the Community Land Model with Coupled Carbon and Nitrogen

Abstract:

Soils are among the largest emission sources of nitrous oxide (N₂O), which is a strong greenhouse gas and is the leading stratospheric ozone depleting substance. Thus, there is a rising concern for mitigating N₂O emissions from soils. And yet, our understanding of the global magnitude and the impacts of soil N₂O emissions on the climate and the stratospheric ozone layer is still limited, and our ability to mitigate N₂O emissions thus remains a challenge. One approach to assess the global magnitude and impacts of N₂O emissions is to use global biogeochemical models. Currently, most of these models use a simple or a conceptual framework to simulate soil N₂O emissions. However, if we are to reduce the uncertainty in determining the N₂O budget, a better representation of the soil N₂O emissions process is essential. In our attempts to fulfill this objective, we have further improved the parameterization of soil N₂O emissions in the Community Land Model with coupled Carbon and Nitrogen (CLM-CN) by implementing the DeNitrification-DeComposition (DNDC) model and validated our model results to existing measurements. We saw a general improvement in simulated N₂O emissions with the updated parameterization and further improvements for specific sites when the model was nudged with measured soil temperature and moisture data of the respective site. We present the latest updates and changes made to CLM-CN with one-way coupled DNDC model (CLMCN-N₂O) and compare the results between model versions and against other global biogeochemical models.