Regional to national constraints on US N2O emissions using atmospheric data

This presentation will discuss several efforts to use atmospheric data to estimate nitrous oxide (N2O) emissions at regional to national scales across the US. In the past, N2O emissions have been difficult to quantify from atmospheric data because of the large measurement uncertainties relative to the small signal from surface sources. We overcome these challenges to estimate N2O emissions at large scale across the US agricultural belt and at regional scale over the California Central Valley using data collected from tall towers and aircraft, respectively. In general, we find N2O emissions from agriculture that exceed state and national government estimates. Furthermore, we estimate the seasonal cycle of emissions, a cycle that differs between the Great Plains and California. Finally, we will preview the results from an ongoing project to directly estimate emissions factors from fertilizer using atmospheric N2O data.