# Odor Impact Assessment via Dispersion Model: Comparison of Different Input Meteorological Datasets
## 2 Materials and Methods
### Emission Sources  
To conclude the set of input variables required by the model, it is necessary to characterize the source term. Two different emission scenarios were hypothesized: the first, involving a point source (i.e., an odor emission abatement system); the second, an area source (i.e., a wastewater treatment tank). Both sources were positioned in the center of each simulation domain.  
Characterization involves defining the geometrical parameters of the emission source as well as physical-chemical variables (e.g., temperature and velocity).  
Figure 1: Position of the two sites in Italy and Cuba.  
Figure 2: Terrain elevations for the Cuban domain (**left**) and Italian domain (**right**).  
More specifically, for area sources, CALPUFF requires the definition of specific dimensional parameters: the dimension and height of the tank and the initial vertical dispersion coefficient, \(\sigma_{z0}\), which identifies the puff's vertical dimension at emission. According to the US-EPA AERMOD User's Guide [48], \(\sigma_{z0}\) should be set by dividing the source's vertical dimension (i.e., height) by 2.15. This numerical coefficient is derived from the Gaussian distribution of the pollutant concentration inside the plume.  
For point sources, it is necessary to define the geometrical dimensions of the emission (i.e., height and diameter), the temperature, and the velocity of the outlet gas.  
Moreover, when considering odor emissions, it is crucial to specify the amount of odor emitted per unit time (Odor Emission Rate, OER), as discussed by [PERSON] [49]. Concerning emissions from area sources, the emissive parameter commonly referenced is the Specific Odor Emission Rate (SOER), i.e., the emission flow per square meter of the source. In addition, for area sources, as suggested by recent investigations [50; 51], the odor emission rate was considered constant, as no hourly profile information is available, and it is not affected by wind velocity.  
The parameters for the point and area sources are reported in Table 3. In both cases, no temporal variability of the emission is considered.  
An additional parameter required to run the CALPUFF simulation is MDISP. It represents the method used to compute horizontal and vertical dispersion coefficients. As suggested by the US-EPA, a value of 2 was adopted for the MDISP parameter, which represents the calculation of turbulence-based dispersion coefficients from micrometeorological variables [40; 42].  
In addition to comparing the different odor impact maps resulting from the model runs, further evaluations were made by estimating the odor concentrations at a set of selected discrete receptors. A receptor nest was created by placing 324 receptors, radially separated by an angle of 20\({}^{\circ}\), at distances of 50, 100, 150, 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, and 3000 m from the source center, following the strategy outlined by [29].  
In Table 4, below, the input parameters used in the simulations are summarized for both domains and for the different meteorological settings.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Point Source** & & \\ \hline Height & 9 & [m] \\ Diameter & 1.2 & [m] \\ Odor Emission Rate (OER) & 2000 & [\(\mathrm{ou_{E}/s}\)] \\ Exit temperature & 313 & [K] \\ Exit velocity & 5.4 & [m/s] \\ \hline
**Area Source** & & \\ \hline Height & 3 & [m] \\ \(\sigma_{z0}\) & 1.4 & [m] \\ Odor Emission Rate (OER) & 3500 & [\(\mathrm{ou_{E}/s}\)] \\ Specific Odor Emission Rate (SOER) & 1.39 & [\(\mathrm{ou_{E}/m^{2}/s}\)] \\ Length X & 42 & [m] \\ Length Y & 60 & [m] \\ \hline \hline \end{tabular}
\end{table}
Table 3: Point and area source characterization.