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HIGH TIME-RESOLVED COMPARISONS FOR IN-DEPTH PROBING OF CMAQ FINE-PARTICLE AND GAS PREDICTIONS
Citation:
Dennis, R L., S J. Roselle, R Gilliam, AND J. R. Arnold. HIGH TIME-RESOLVED COMPARISONS FOR IN-DEPTH PROBING OF CMAQ FINE-PARTICLE AND GAS PREDICTIONS. Presented at 27th NATO/CCMS International Technical Meeting on Air Pollution Modeling and its Application, Banff, Canada, October 25-29, 2004.
Impact/Purpose:
The goal of this task is to thoroughly characterize the performance of the emissions, meteorological and chemical/transport modeling components of the Models-3 system, with an emphasis on the chemical/transport model, CMAQ. Emissions-based models are composed of highly complex scientific hypotheses concerning natural processes that can be evaluated through comparison with observations, but not validated. Both performance and diagnostic evaluation together with sensitivity analyses are needed to establish credibility and build confidence within the client and scientific community in the simulations results for policy and scientific applications. The characterization of the performance of Models-3/CMAQ is also a tool for the model developers to identify aspects of the modeling system that require further improvement.
Description:
Input errors affect model predictions. The diurnal behavior of two inputs NHx, which partitions in the inorganic system between gas and particle, and EC, a nonreactive emitted specie, is compared for CMAQ predictions and observations. A monthly average diurnal profile based on hourly data is the basic unit for the comparisons with CMAQ predictions, with special investigations of time series to further examine the average behavior. Hourly measurements are available for August 1999 in the Atlanta, GA area and January 2002 for Atlanta, GA, Pittsburgh, PA and St. Louis, MO. For NHx, results for Atlanta and Pittsburgh show that there may be an issue with the diurnal emission profile of NH3 in the summer, particularly in the morning, but not in the winter. For EC, cross-species correlations between EC and other species for a.m. and p.m. rush hours and midday time periods for Atlanta indicate that there may be an issue of missing midday sources of EC in the model emissions inventory. Meteorological issues that affect both species will also be pointed out in the comparisons.
The research presented here was performed under the memorandum of understanding between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and under agreement number DW13921548. Although it has been reviewed by EPA and NOAA and approved for publication, it does not necessarily reflect their policies of views.