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AQMEII4 Activity 2 - A single-point modeling approach for the intercomparison and evaluation of ozone dry deposition across regional air quality models
Citation:
Clifton, O., D. Schwede, C. Hogrefe, A. Khan, S. Galmarini, L. Emberson, J. Fleming, C. Holmes, P. Makar, S. Silva, J. Bash, S. Bland, P. Cheung, L. Ganzeveld, V. Huijnen, J. Perez Camanyo, J. Pleim, L. Ran, R. San Jose, S. Sun, A. Tai, M. Coyle, E. Fredj, I. Goded, O. Gazetas, L. Horváth, Q. Li, I. Mammarella, G. Manca, W. Munger, R. Staebler, E. Tas, T. Vesala, T. Weidinger, Z. Wu, AND L. Zhang. AQMEII4 Activity 2 - A single-point modeling approach for the intercomparison and evaluation of ozone dry deposition across regional air quality models. ITM 2023 International Technical Meeting On Air Pollution Modeling And Its Application, Chapel Hill, NC, May 22 - 26, 2023.
Impact/Purpose:
This presentation provides an overview of 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. Initial results from the box model intercomparison will be included in the presentation.
Description:
A primary sink of many air pollutants and their precursors is dry deposition. Dry deposition estimates differ substantially across chemical transport models yet an understanding of the drivers of the inter-model spread is incomplete. Here we introduce Activity 2 of the Air Quality Model Evaluation International Initiative Phase 4 (AQMEII4) aimed at process-oriented evaluation of dry deposition schemes from regional air quality models. We configure the dry deposition schemes as single-point models at a set of eight northern hemisphere locations with multiyear records of observed ozone fluxes. The single-point models are driven by identical meteorological and environmental conditions. Five out of the eight sites examined have at least three and up to twelve years of ozone fluxes. We demonstrate a large model spread in simulated multiyear mean ozone deposition velocities at the sites across months. While some models exhibit only small biases for specific sites and seasons, none of the models are always within 50% of the observed multiyear average across all sites and seasons. Some models capture the observed seasonality (e.g., amplitude and phase of the seasonality), while others do not, or create more seasonality than is observed. For the first time, we quantify how the contributions from different depositional pathways vary across models. Even when models agree in terms of the magnitude of the deposition velocities, they can disagree in terms of contributions from the different pathways. The results shown here are the beginning of results anticipated from AQMEII4 Activity 2, which brings scientists who model air quality together with scientists who measure ozone fluxes to evaluate and improve the dry deposition schemes in the chemical transport models used for research and regulatory purposes.