# Comparing Monitoring Networks to Assess Urban Heat Islands in Smart Cities
## 6 Discussion of Results
### Concerning the Choice of Components and Programming of the System  
A fundamental distinction lies in the flexibility of purpose-built monitoring systems, which can be tailored to specific research needs. These systems allow for customization of AWS components such as sensor type, resolution, uncertainty, radiation shielding, power supply (e.g., deep sleep mode), sampling frequency, transmission protocol, clock synchronization, and data storage. Additionally, open-source firmware enables users to implement advanced functionalities like alarms, quality control, and remote calibration, enhancing transparency and control. In contrast, CWONs often rely on closed-source hardware and software. This limits users' understanding of system constraints, which can compromise data interpretation. \begin{table}
\begin{tabular}{c c c c} \hline  & **Bs** & **Nt** & **WU** \\ \hline Uniformity of devices & Yes & Partially & No \\ Uniformity of device locations & Partially & No & No \\ \hline Sensor’s characteristics & & & *1 \\ \hline Temperature range & Partially & Partially & Partially \\ Temperature accuracy & Partially & Partially & No \\ Temperature resolution & Yes & Yes & Yes \\ Relative humidity range & Yes & Yes & Yes \\ Relative humidity accuracy & No & No & No \\ Relative humidity resolution & Yes & Yes & Yes \\ Rugged, low-maintenance, and minimally distorted & Yes & Yes & *1 \\ \hline Air temperature control elements & & & \\ \hline Radiation screen & Yes & - & -*1 \\ Ventilated radiation screens & Yes & Yes & *1 \\ Forced ventilation & No & No & *1 \\ Materials and thermal conductivity & Yes & Yes & *1 \\ Diameter and height & No & No & *1 \\ \hline Sampling frequency and accuracy & & & *1 \\ \hline Minimum sampling interval & Yes & Yes & Yes *1 \\ Local storage or preferred RTD & Yes & Yes & Yes \\ Prioritizing automatic stations with respect to manual stations & Yes & Yes & Yes \\ \hline Height and location of sensors & & & \\ \hline Sensor height & Yes & - & - \\ Proximity and distance to obstacles & Yes & - & - \\ Location with representative HUZ & Yes & Partially & Partially \\ \hline Calibration and quality control & & & \\ \hline Sensors periodic calibration in laboratory or on-site & *2 & - & - \\ Reporting of the periodic calibrations & *2 & No & No \\ \hline Automatic quality control & Verification of data: continuity, stability and consistency & Partially & Partially \\ Comparison with nearby stations & No & Yes & Yes \\ \hline Metadata & GPS coordinates and altitude & Yes & No & No \\ Sensor type and model & Yes & Yes & No \\ Installation date & Yes & No & No \\ Maintenance & Yes & No & No \\ \hline \end{tabular}  
*1 It depends on the model; *2 Not yet.  
\end{table} 
Table 3: Summary of the considerations of WMO recommendations by the networks mentioned in the paper. Moreover, the heterogeneity of CWON equipment (due to varying AWS models or the absence of optional components like radiation shielding or forced ventilation) can lead to inconsistencies in data quality that cannot be fully corrected, even with post-processing quality control. All networks analyzed use low-cost RTD-based AWSs, which meet WMO standards for temperature measurement in UHI studies. However, power supply remains a challenge. Battery-powered AWSs require periodic replacement, which can be logistically complex and costly, especially for remote installations, as evidenced by the case of the purpose-built monitoring situated far from facades. In contrast, CWON devices, typically installed in accessible domestic settings, are easier to maintain. Solar panels offer greater autonomy but require higher initial investment and are dependent on sunlight availability, often necessitating battery backups, as observed with select AWSs offered by WU. Data transmission protocols also play a crucial role. LoRaWAN, for example, offers long-range, low-power communication and supports scalable, open-technology infrastructures. This enables integration with broader smart city applications--such as mobility and waste management--beyond UHI monitoring.