You are here:
Observation-based estimate of field-scale dry deposition across the U.S. Ammonia Monitoring Network (AMoN)
Citation:
Baublitz, C., JohnT Walker, J. Bash, AND Z. Wu. Observation-based estimate of field-scale dry deposition across the U.S. Ammonia Monitoring Network (AMoN). American Meteorological Society Annual Conference, Denver, CO, January 08 - 12, 2023.
Impact/Purpose:
The dry deposition of ammonia is a large, and growing, contributor to the total atmospheric input of nitrogen (N) to U.S. ecosystems and waterways, where excess N may impair ecological services and eutrophy drinking water resources. Here we develop and evaluate a tool that simulates field-scale dry deposition fluxes across the U.S. Ammonia Monitoring Network (AMoN). It provides a new path forward for characterizing uncertainty in ammonia dry deposition and to explore the sensitivity of this process to individual drivers.
Description:
Direct measurements of ammonia dry deposition are sparse, such that the drivers of its spatiotemporal variability are not well understood. Here we develop a tool that simulates field-scale dry deposition fluxes across the U.S. Ammonia Monitoring Network (AMoN). The tool uses publicly available, observation-based datasets and the model for Surface Tiled Aerosol and Gaseous Exchange (STAGE). After evaluating this framework using observations from a set of three pilot sites that span a range of average ammonia concentration, climatology and land cover, we apply the tool to investigate the spatiotemporal variability of dry deposition across AMoN in 2018. With additional sensitivity simulations, we also test the influence of individual processes and empirical model parameters on the component (vegetation and ground) ammonia fluxes. Preliminary results indicate that the largest total fluxes occur in Colorado, Texas and Utah, generally driven by comparably high measured ammonia concentrations. Our bi-directional parameterization suggests that the overall net flux of shrublands is upward, such that the AMoN sites with this land cover class may serve as an under-appreciated source of ammonia. This also implies that measurements of ammonia dry depositional fluxes over this ecosystem type could facilitate improved constraints on the representation of bi-directional ammonia fluxes over the USA. Overall, this tool provides a new path forward for characterizing uncertainty in ammonia dry deposition and to explore the sensitivity of this process to individual drivers, for example due to projected shifts in meteorology with climate change.