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AQMEII 4 Deposition: Detailing the Ongoing Fourth Phase of the Air Quality Model Evaluation International Initiative
Citation:
Galmarini, S., C. Hogrefe, P. Makar, J. Ducker, C. Holmes, S. Silva, O. Clifton, D. Schwede, L. Emberson, J. Bieser, J. Flemming, AND M. Schaap. AQMEII 4 Deposition: Detailing the Ongoing Fourth Phase of the Air Quality Model Evaluation International Initiative. 37th International Technical Meeting on Air Pollution Modeling and its Application, Hamburg, GERMANY, September 23 - 27, 2019.
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. As AQMEII has finished its third phase, planning has begun to initiate a fourth phase with a focus on atmospheric deposition. Presenting these plans to the atmospheric modeling community present at the ITM is expected to lead to valuable feedback and help inform the research to be performed during AQMEII Phase 4.
Description:
The Air Quality Model Evaluation International Initiative (AQMEII) has entered its fourth phase of activities. The focus of this phase will be on deposition, a key process in any air quality modelling, and especially in regional scale models. Since deposition determines the removal of species from the air, itis effectively a boundary condition to the simulation of ambient concentrations. Furthermore the deposited species affect ecosystems and the determination of the critical loads is of paramount importance for policy action. Past assessments, including those performed within AQMEII, have demonstrated that a large uncertainty exists within modeling the deposition process, in the way different models handle information like land use to determine deposition velocities. While only a limited number of schemes are available, the differences among models results can be significant depending on the level of detail that is included in the former. The goal of this fourth phase is to set up a more diagnostic approach to the evaluation of this process, therefore dissecting the key elements of deposition modeling and comparing the behaviors of models. The research questions addressed are listed below: • How well do the simulated deposition fields agree with available observations? • Do models with seemingly similar deposition schemes predict similar deposition? If not, why? • What are the effects of three key factors (day vs. night, summer vs. winter, and dry vs. wet) on simulated dry deposition velocity? • How large are inter-model dry deposition differences under “standard” conditions compared to inter-model differences with varying meteorology? • How does simulated dry deposition velocity vary across land cover types and between models under “standard meteorological conditions”? • How and why do current dry deposition models differ under identical environmental conditions? • How well do these models predict measured deposition velocity? • Quantify the sensitivity of dry deposition velocity to changes in individual environmental factors and surface conditions. • How can an ensemble of simulated meteorological, concentration, and deposition fields, along with observations, best be used to calculate maps of total deposition and critical load exceedances? • How does variability in simulated deposition translate into uncertainty in policy-relevant critical load estimates? How does this compare to the uncertainty caused by using different critical load data sets? Details on the ongoing modeling activity will be provided during the talk including specification of the different types of modeling exercises designed to address the research questions above.