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AQMEII4 Ensemble Estimates of Sulphur and Nitrogen Deposition in North America and Europe: Initial Results and Comparisons to Metrics of Ecosystem Damage
Citation:
Makar, P., P. Cheung, I. Kioutsioukis, H. Cathcart, A. Cole, J. Lynch, M. Bell, T. Scheuschner, A. Hodzic, Y. Ryu, A. Lupascu, T. Butler, R. San Jose, J. Perez Camanyo, R. Kranenburg, C. Hogrefe, J. Bash, J. Pleim, D. Schwede, U. Alyuz, K. Momoh, R. Sokhi, R. Bellasio, R. Bianconi, O. Clifton, AND S. Galmarini. AQMEII4 Ensemble Estimates of Sulphur and Nitrogen Deposition in North America and Europe: Initial Results and Comparisons to Metrics of Ecosystem Damage. 2023 International Technical Meeting On Air Pollution Modeling And Its Application, Chapel Hill, NC, May 22 - 26, 2023.
Impact/Purpose:
This presentation is based on an analysis of nitrogen, sulfur and ozone deposition fields and associated diagnostic variables modeled by participants in Phase 4 of the Air Quality Model Evaluation International Initiative (AQMEII). AQMEII is a collaboration between North American and European regional air quality modelers and is being co-chaired by EPA and the European Commission Joint Research Centre. AQMEII is currently conducting its fourth phase of research with a focus on atmospheric deposition. The research effort includes box modeling at flux measurement sites and continental-scale annual grid model simulations. Results from the activity are expected to help guide future development of dry deposition representation in photochemical models and inform the use of modeled deposition fields for impact assessments.
Description:
Activity 1 of the Air Quality Model Evaluation International Initiative, Phase 4 (AQMEII-4) has as its focus a highly detailed intercomparison of regional air-quality model deposition codes, with a particular emphasis on gas-phase deposition and its component resistances and conductances. Multiple regional model simulations were carried out for 2 years using common emissions inputs in both Europe and North America, with concentration, deposition fluxes, and a comprehensive set of gas-phase diagnostic deposition outputs contributed from participating modelling groups. Native gridded model output was converted to a common 0.125ox0.125o grid for both domains. A preliminary evaluation of the ensemble of the model performance against available air concentration and wet deposition measurements appears elsewhere in this ITM (Kioutsioukis et al, 2023). Here, we focus on the comparison of the ensemble members and ensemble mean predicted deposition fluxes for Sulphur, Nitrogen and O3, and characterize the range of environmental impacts inferred from those flux estimates. We then delve into the underlying reasons for the differences between predicted annual fluxes from ensemble members, using the AQMEII4 diagnostic deposition package and the relative contributions of wet, dry and particulate deposition. Specific resistances and conductance pathways explaining the differences will be identified. We will also identify cases where models have similar total deposition results, but arrive at the totals via different assumptions regarding the strength of deposition pathways. These analyses will be used to identify key uncertainties in current deposition algorithms used in regional air-quality models.
