# Evaluation of Different Chemical Mechanisms on O3 and PM2.5 Predictions in Alberta, Canada
## 2 Materials and Methods
### Emissions  
In this study, the 2013 Alberta emission database was used, which was developed by harmonizing several emission sources from regional, provincial, and national levels [40; 41; 42]. The data sources and development methodology are described elsewhere [10]. Table 2 presents emissions breakdowns based on points and area sources as well as based on the oil and gas sector for each pollutant. The biogenic model, MEGAN 2.1 (Model of Emissions of Gases and Aerosols from Nature), was applied using daily meteorology from the WRF model to generate daily emissions. Land cover variables such as emission factors, leaf area index, and plant functional types were taken from the biospheric atmospheric interactions group at the University of California Irvine [43].  
In the modelling domain, total SO\({}_{2}\), NOx, and VOCs emissions in 2013 were approximately 17.5 kt, 102 kt, and 56.1 kt, respectively. The major contributors to SO\({}_{2}\) and NOx emissions are oil and gas point sources, while primary PM\({}_{10}\) and PM\({}_{2.5}\) emissions are released predominantly from area sources. Since the model is run for emissions in July and December, spatial distribution of various pollutants in these months are presented in Figure 2. The emissions are observed to be high near Grande Prairie and Beaverlodge in the north and Edson in the south. Dense concentrations are also observed towards northwest and southeast of the domain likely due to the boundary conditions, i.e., the terrain is becoming significantly elevated towards the southwest. NOx and PM\({}_{2.5}\) are slightly higher in July, while VOCs are higher in December (Figure 2).  
\begin{table}
\begin{tabular}{c c} \hline
**Model Option** & **Configuration** \\ \hline Horizontal Grid Mesh & 4 km \\ Vertical Grid Mesh & 22 layers up to 100 mb \\ Gas-Phase Chemistry & CB6R3, SAPRC07 and RACM2 \\ Aerosol Chemistry & AE6 \\ Secondary Organic Aerosols & SORGAM \\ Meteorological Processor & MCIP Version 4.4 \\ Horizontal Transport & PPM \\ Horizontal Diffusion & K-theory spatially varying \\ Vertical Advection Scheme & Yamartino \\ Vertical Eddy Diffusivity Scheme & ACM2 \\ Diffusivity Lower Limit & Kzmin = 0.01 to 2.0 m\({}^{2}\)/s (PURB option) (KZMIN set to true) \\ Deposition Scheme & M3 dry \\ Land Surface Model (LSM) & Noah \\ \hline \end{tabular}
\end{table}
Table 1: CMAQ model 5.3.2 configuration.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Type** & \multicolumn{6}{c}{**Emissions (tonnes)**} \\ \cline{2-7}  & **SO\({}_{2}\)** & **NO\({}_{X}\)** & **VOCs** & **PM\({}_{10}\)** & **PM\({}_{2.5}\)** & **CO** & **NH\({}_{3}\)** \\ \hline Point Sources Oil and Gas Extraction & 15,437 & 57,712 & 31,605 & 799 & 739 & 55,391 & 17 \\ Point Sources Other than Oil and Gas Extraction & 1794 & 6051 & 2040 & 1173 & 811 & 9789 & 67 \\ Area Sources (biogenic, on-road, off-road, & & & & & & \\ residential/commercial, industrial target stacks), waste management, road, fugitive, construction dust) & 315 & 39,058 & 22,466 & 146,828 & 45,706 & 79,994 & 9651 \\ \hline Total & 17,546 & 102,821 & 56,111 & 148,800 & 47,256 & 145,174 & 9735 \\ \hline \end{tabular}
\end{table}
Table 2: 2013 Annual point and area emission sources of primary pollutants in the modelling domain.  
Figure 2: 2013 Spatial distribution of NOx, VOC, and PM\({}_{2.5}\) emissions in July (top) and December (bottom) in the modelling domain. (**a**) NOx (summer), (**b**) VOC (summer), (**c**) PM\({}_{2.5}\) (summer), (**d**) NOx (vintner), (**e**) VOC (vintner), (**f**) PM\({}_{2.5}\) (vintner).