Citation:

Dennis, R. AIR QUALITY MODELING OF AMMONIA: A REGIONAL MODELING PERSPECTIVE. Presented at Ammonia Workshop, Washington, DC, October 23-24, 2003.

Impact/Purpose:

This task has the following objectives:

Improve modelers' ability to focus on scientific and policy issues in modeling studies by providing software that supports composing, applying, and evaluating complex systems of models.

Improve the understanding of the interaction of the atmosphere and the underlying surface, especially the flux of mass in both directions, and EPA's ability to simulate that interaction.

Contribute to multimedia studies and assessments by applying state-of-the-art atmospheric models, estimating atmospheric contributions to multimedia issues and the sources of those contributions, and evaluating the models' strengths and weaknesses.

Description:

The talk will address the status of modeling of ammonia from a regional modeling perspective, yet the observations and comments should have general applicability. The air quality modeling system components that are central to modeling ammonia will be noted and a perspective on their contribution to the overall uncertainty will be given. Special attention to the overall importance of ammonia emissions and their uncertainty will be given with illustrations from inverse modeling. The capability of our physical and chemical modeling of the ammonia part of the inorganic system will be put in perspective vis a vis the overall inorganic system uncertainties. Issues related to estimating the dry deposition of ammonia will be noted. The large uncertainty in interpretations of the ammonia budget will then be raised, including our poor understanding of the regional or continental budget. Perspectives on local versus long-range transport from regional analyses will be given, modeled budget analyses will be presented and some discrepancies with conventional wisdom noted. This leads into a further discussion of issues that can affect attribution and introduce biases. The talk concludes with a set of recommendation of research directions that will help improve the modeling of ammonia, support better evaluation of models and aid interpretation of the ammonia system.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official agency policy.

Record Details: