Critical load exceedances for North America and Europe using an ensemble of models and an investigation of causes of environmental impact estimate variability: an AQMEII4 study

Makar, Paul A.; Cheung, Philip; Hogrefe, Christian; Akingunola, Ayodeji; Alyuz, Ummugulsum; Bash, Jesse O.; Bell, Michael D.; Bellasio, Roberto; Bianconi, Roberto; Butler, Tim; Cathcart, Hazel; Clifton, Olivia E.; Hodzic, Alma; Kioutsioukis, Ioannis; Kranenburg, Richard; Lupascu, Aurelia; Lynch, Jason A.; Momoh, Kester; Perez-Camanyo, Juan L.; Pleim, Jonathan; Ryu, Young-Hee; San Jose, Roberto; Schwede, Donna; Scheuschner, Thomas; Shephard, Mark W.; Sokhi, Ranjeet S.; Galmarini, Stefano

doi:https://doi.org/10.5194/acp-25-3049-2025

Articles | Volume 25, issue 5

https://doi.org/10.5194/acp-25-3049-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

AQMEII4: a detailed assessment of atmospheric deposition processes...

https://doi.org/10.5194/acp-25-3049-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 5

Research article

|

14 Mar 2025

Research article |

| 14 Mar 2025

Critical load exceedances for North America and Europe using an ensemble of models and an investigation of causes of environmental impact estimate variability: an AQMEII4 study

Paul A. Makar, Philip Cheung, Christian Hogrefe, Ayodeji Akingunola, Ummugulsum Alyuz, Jesse O. Bash, Michael D. Bell, Roberto Bellasio, Roberto Bianconi, Tim Butler, Hazel Cathcart, Olivia E. Clifton, Alma Hodzic, Ioannis Kioutsioukis, Richard Kranenburg, Aurelia Lupascu, Jason A. Lynch, Kester Momoh, Juan L. Perez-Camanyo, Jonathan Pleim, Young-Hee Ryu, Roberto San Jose, Donna Schwede, Thomas Scheuschner, Mark W. Shephard, Ranjeet S. Sokhi, and Stefano Galmarini

Supplement

https://doi.org/10.5194/acp-25-3049-2025-supplement

Data sets

Air Quality System (AQS) US EPA https://www.epa.gov/aqs

National Trends Network National Atmospheric Deposition Program (NADP) https://nadp.slh.wisc.edu/networks/national-trends-network/https://nadp.slh.wisc.edu/networks/national-trends-network/

AMoN Data Retrieval page National Atmospheric Deposition Program (NADP) https://nadp2.slh.wisc.edu/data/AMoN/

National Air Pollution Surveillance Program Government of Canada https://www.canada.ca/en/environment-climate-change/services/air-pollution/monitoring-networks-data/national-air-pollution-program.html

National atmospheric chemistry database and analysis facility Government of Canada https://www.canada.ca/en/environment-climate-change/services/air-pollution/monitoring-networks-data/national-atmospheric-chemistry-database.html

EMEP European Monitoring and Evaluation Program (EMEP) https://www.emep.int/

Download of historic Airbase air quality data (2000-2012), Discover Map Series AIRBASE https://discomap.eea.europa.eu/map/fme/AirQualityExportAirBase.htm

Model code and software

US EPA Office of Research and Development, CMAQ (5.3.2) US EPA https://doi.org/10.5281/zenodo.4081737

LOTOS-EUROS Open Source Version TNO https://airqualitymodeling.tno.nl/lotos-euros/open-source-version/

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Short summary

The large range of sulfur and nitrogen deposition estimates from air quality models results in a large range of predicted impacts. We used models and deposition diagnostics to identify the processes controlling atmospheric sulfur and nitrogen deposition variability. Controlling factors included the uptake of gases and aerosols by hydrometeors, aerosol inorganic chemistry, particle dry deposition, ammonia bidirectional fluxes, gas deposition via plant cuticles and soil, and land use data.