Citation:

Hogrefe, C., G. Pouliot, J. Xing, S. Roselle, R. Mathur, J. Flemming, AND S. Galmarini. Global and Regional Modeling of Long-Range Transport and Intercontinental Source-Receptor Linkages (presentation). The 34th International Technical Meeting on Air Pollution Modeling and Its Application, Montpellier, FRANCE, May 04 - 08, 2015.

Impact/Purpose:

The National Exposure Research Laboratory’s Atmospheric Modeling Division (AMAD) conducts research in support of EPA’s mission to protect human health and the environment. AMAD’s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation’s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.

Description:

Because long-range transport has been shown to affect air quality in downwind continents, there is a growing realization that these effects may need to be considered in air quality management efforts by distinguishing between the contributions of local and regional emission sources and the contributions due to long-range transport. This study, performed within the context of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) and the task force on Hemispheric Transport of Air Pollution (HTAP), applies and compares several modeling approaches to quantify long-range transport. One of these modeling approaches is the application of global models in which long-range transport is modeled for current conditions and various emission perturbation scenarios. However, given the global coverage of these models, grid resolution is often on the order of one to several hundred kilometers which may be inadequate to resolve the lofting of pollutants in source regions and the downward mixing of transported pollution to the surface in receptor regions. An alternate modeling approach links global and regional scale models to potentially improve upon the representation of vertical mixing processes. We first compare air quality over North America simulated for the year 2010 by the MACC-HTAP global model and the CMAQ regional model driven by boundary conditions from MACC-HTAP against surface and upper air observations. The second objective is to analyze the impacts of perturbed emissions in East Asia and North America on air quality over North America simulated by global and linked global/regional models and compare and contrast the source-receptor linkages estimated by both approaches. Both aspects of this study are aimed at determining the differences between the two modeling approaches in quantifying long range transport of air pollution and its impact on local air quality.

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