## 3 Results  
For numerical simulation, the parameters from Table 1 were used. Figure 3 shows the wind speed field at ground level (\(z\) = 0 m). Approximately, the average speed along the \(u\)-axis is about 5.43 m/s (average value over the entire area), maximum \(\approx\) 7.80 m/s, and minimum \(\approx\) 3.20 m/s; the resulting speed has an average value of about 5.50 m/s and a maximum of \(\approx\) 9.25 m/s. At ground level (\(z\) = 0 m), the air velocity (see Figure 3a) is characterized by comparatively low values: the average velocity is about 0.76 m/s, with the maximum value reaching 1.67 m/s. This is typical for the boundary layer, where the influence of surface friction is significant. At a height of 131.6 m (see Figure 3b), the average velocity increases to 1.66 m/s, which reflects the decrease in the influence of surface friction. At a height of 263.2 m (see Figure 3c), the average velocity reaches 2.24 m/s, and at a level of 500 m (see Figure 3d), it is already 3.01 m/s with a maximum value of up to 4.0 m/s. The analysis presented in Table 2 confirms the presence of velocity gradients in the horizontal plane, which is visible in the distribution of vectors in the velocity field \begin{table}
\begin{tabular}{c c} \hline
**Description** & **Value** \\ \hline Area dimensions, \(L_{x}\times L_{y}\times L_{z}\) & 1000 \(\times\) 1000 \(\times\) 500 m \\ Computational grid sizes, \(N_{x}\times N_{y}\times N_{z}\) & 100 \(\times\) 100 \(\times\) 50 \\ Step in \(x\) direction, \(\Delta x\) & 25 m \\ Step in \(y\) direction, \(\Delta y\) & 25 m \\ Step in \(z\) direction, \(\Delta z\) & 20 m \\ Time step \(t\), \(\Delta t\) & 1 s \\ Total simulation time & 3600 s (1 h) \\ Diffusion coefficient for contamination & 5.0 m\({}^{2}\)/s \\ Diffusion coefficient for temperature & 2.0 m\({}^{2}\)/s \\ Maximum speed (advection) & 4.0 m/s \\ Peclet number for contamination & by \(x\) 800, by \(z\) 400 \\ Peclet number for temperature & by \(x\) 2000, by \(z\) 1000 \\ Stability condition & CFL \(<\) 1 \\ \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters. Figure 3: Distribution of wind speed field at (**a**) \(z=0\), (**b**) \(z=131.6\), (**c**) \(z=263.2\), (**d**) \(z=500\) m. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Time (s)**} & **Mean Concentration** & **Maximum Concentration** & **Total Mass** \\  & **(\(\mu\)g/m\({}^{3}\))** & **(\(\mu\)g/m\({}^{3}\))** & **(\(\mu\)g/m\({}^{3}\))** \\ \hline
0 & 0.8 & 100 & 437,317,784.26 \\
900 & 0.06 & 3.59 & 34,312,776.64 \\
1800 & 0 & 0.59 & 2,588,394.67 \\
2700 & 0 & 0.04 & 191,033.42 \\
3600 & 0 & 0 & 14,043.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Analysis of concentration. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Time (s)**} & **Mean Temperature** & **Maximum** & **Minimum** \\  & **(\({}^{\circ}\)C)** & **Temperature (\({}^{\circ}\)C)** & **Temperature (\({}^{\circ}\)C)** \\ \hline
0 & 14.06 & 25 & 8 \\
900 & 14.02 & 18.96 & 9.49 \\
1800 & 14 & 18.12 & 9.96 \\
2700 & 14 & 17.69 & 10.32 \\
3600 & 14 & 17.38 & 10.63 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Analysis of temperature. Figure 5: Distribution of pollution concentration at (**a**) \(z=0\), (**b**) \(z=131.6\), (**c**) \(z=263.2\), (**d**) \(z=500\) m.  
The obtained data (see Table 2) demonstrate that the model adequately describes the dynamics of the wind flow: an increase in speed with height indicates a decrease in the effect of surface friction, and the horizontal distribution shows the distribution of air movement speed characteristic of the layer boundaries. Figure 4 shows temperature profiles (in \({}^{\circ}\)C) for different altitude levels (approximately: \(z=0\) m, \(z\approx 131.6\) m, \(z\approx 263.2\) m, and \(z=500\) m). At ground level, the temperature has average values of about 17.37 \({}^{\circ}\)C, and at the upper boundary (\(z=500\) m) it is about 10.63 \({}^{\circ}\)C, which reflects the vertical temperature gradient.