Evaluating the Relative Importance of Direct and Indirect Agricultural N2O Emissions over the United States Using Forward Modeling and Atmospheric N2O and River Nutrient Data

The goal of the project is to quantify the relative magnitude, spatial distribution and timing of direct and indirect agricultural N2O emissions by means of a set of forward model simulations using the coupled Community Land Model-River Transport Model (CLM-RTM). The terrestrial model simulations will be combined with a set of atmospheric chemistry tracer transport models, on both regional scales, focusing on the United States (WRF-Chem without stratospheric chemistry) and global scales (Community Atmospheric Model (CAM) with full stratospheric chemistry) to examine impacts of terrestrial emissions on atmospheric variability in N2O at U.S. and global monitoring sites. Comparison of atmospheric model results to NOAA flask, aircraft and tall tower N2O data will provide a basis for evaluating the models as well as understanding how current NOAA data products may bias regional model results, e.g., by neglecting remote influences such as the seasonal stratospheric influx.