2.14 A Comparison of Multiple Ozone and Particulate Matter Source Apportionment Models

摘要

Both models tend to under-predict ozone greater than 75 ppb. The relationship between estimated ozone contribution over all receptors from all source regions is strong between CAMx and CMAQ. Most of the variability in the error is due to differences in contribution estimates from the boundary and the group consisting of all other emissions in the modeling domain that were not tagged. CAMx and CMAQ are fairly consistent with absolute model estimates of PM2.5 species, with the exception of nitrate ion, of which CMAQ tends to predict higher concentrations. The modeling systems also tend to have strong relationships in predicted source contributions. Again, nitrate ion source contribution between models has the weakest relationship of the species examined in this study. The largest contributing species on the top 10% of modeled days include primarily emitted species including primary organic carbon and elemental carbon. Contributions from source areas furthest away from the Milwaukee/Waukesha area tend to be dominated by secondarily formed species such as nitrate ion and sulfate ion. Despite differences in model formulations, the source contributions estimated by each modeling system compare well with each other. This increases the confidence that each is appropriately implemented and suitable for the estimation of source contribution.