# Evaluation of the Urban Weather Generator on the City of Toulouse (France)
## 2 Materials and Methods
### UWG: Urban Weather Generator Model
#### 2.2.2 Model Input and Output Data
These indicators have been computed at 50 cm resolution from BD ORTHO [48]. This has been performed using specific vegetation classification criteria mixed with deep neural networks [49; 50; 51]. Results have been refined by Computer-Assisted Photo Interpretation (CAPI) [51]. 3. _City information._ This optional information is provided by city planners and mainly corresponds to the buildings' construction era, their nature (residential, commercial, etc. ), and the associated LCZ. The parameters modified (from default values) in this study are detailed in Table 4. The surface parameters are first generated at the native spatial resolution of the initial dataset (50 cm or 1 m) and then aggregated at 200 m using a convolution kernel. Among optional parameters in UWG, the main ones we modified are all linked to **atmospheric** conditions, and in particular:  
* The Daytime Urban Boundary Layer height in meters, noted h_ubl1;
* The Nighttime Urban Boundary Layer height in meters, noted h_ubl2;
* The Reference Height in meters, noted h_ref. As explained in [45], the reference height is the height at which temperature profiles are uniform (default value = 150 m). In some resources, reference height is confused with inversion height, which is the height at which the capping inversion occurs (default value = 1000 m). Capping inversion occurs when the normal temperature (warm air below, cold air above) profile is reversed. This height is the same as the boundary layer height at daytime). \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Group** & **Parameter** & **Description** & **Carmes** \\ \hline Urban Characteristics & bldHeight & Building Height (meters) & 16.71 \\ \hline Urban Characteristics & bldDensity & Building Density (ratio ranging between 0 and 1 & 0.51 \\ \hline  & & Vertical To Horizontal, also called the & \\  & & & facade-to-site ratio in some resources on \\  & & UWG. It is the ratio of the vertical & \\ Urban Characteristics & verToHor & surface area (walls) to the urban plan & \\  & & area. It is defined by: \(\sum\frac{P\,h_{nat}}{A}\,_{site}\), & \\  & & where \(P=building\, perimeter\), & \\  & & \(h_{nat}=average\)\(building\)\(height\), & \\  & & weighted by footprint, and & \\  & & \(A_{site}=total\)\(site\)\(area\)[28]. & \\ \hline Vegetation & & Grass Coverage, proportion of grass & \\ Parameters & grasscover & (ratio ranging between 0 and 1). & \\ \hline Vegetation & & treecover & tree Coverage, the proportion of trees in \\ Parameters & treecover & the studied area (ranging between 0 and 1). & \\ \hline  & & The American Society of Heating, & \\ City Information & Climate & Refrigerating and Air-Conditioning & \\  & Zone & (ASHRAE) classify International & \\  & & Zone & Stations of different countries/zones all \\  & & around the world into 9 great classes & \\  & & (from 0 to 8) and 19 sub-classes [52]. & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: **Surface parameters of UWG modified in our study. **The UWG model outputs simulated values for air temperatures and humidity [29]. Let us now discuss the evaluation methodology.