# Comparing Monitoring Networks to Assess Urban Heat Islands in Smart Cities
## 3 Choice of System Components and Programming
### Citizen Weather Observer Networks
#### 3.3.1 Automatic Weather Stations  
Both networks are RTD. The AWSs of Nt are: light (measuring temperature, relative humidity, and atmospheric pressure) or all in one, while the WU can integrate AWSs of various commercial brands with different characteristics, although the majority are Basic (adding rainfall and wind speed and direction) or Compact AWS. Figure 3: (**a**) Characteristics of the communication device antenna, radiation pattern. (**b**) Appearance of the communication device. (**c**) Inside the waterproof box. 1. Sensors, central processing unit, and peripheral equipment The AWS of Nt integrates the sensors, the central processing unit, and the peripheral equipment in a compact, aluminum anodized module with the following dimensions: 45 \(\times\) 45 \(\times\) 105 mm. * The sensor used (SHTC3 [80]) measures temperature in a range from \(-\)40 \({}^{\circ}\)C to 125 \({}^{\circ}\)C, with an accuracy of \(\pm\)0.2 \({}^{\circ}\)C, and relative humidity, within a range of 0% to 100%, offering a typical accuracy of \(\pm\)2%. Measurements have a resolution of 0.01 \({}^{\circ}\)C and 0.01%, respectively. Sensors reported LTD ranging from \(\pm\)0.02 to \(\pm\)0.04 \({}^{\circ}\)C/year. The stations were installed between 2014 and 2024, resulting in accumulated LTD values ranging from \(\pm\)0.02 \({}^{\circ}\)C to \(\pm\)0.39 \({}^{\circ}\)C, depending on the sensor's age. * The CPU automatically acquires the data registered by the sensors and then processes and prepares them for internal dispatch. The data transmission between the AWSs and the Nt server is through a Wi-Fi connection that is compatible with the standard 802.11 b/g/n in the frequency band of 2.4 GHz, reinforced with Open, WEP, WPA, and WPA2-personal security protocols. It enables wireless communication via long-range radio between the interior and exterior module, reaching up to 100 m in open field conditions (868 MHz [81]). * These devices are controlled from a mobile application provided by the manufacturer. It is from this application that the programming is carried out. Many of the operations of the CPU are fixed, programmed from the factory (raw data conversion, local data storage, sampling (five minutes), message coding, and data transmission); as such, it is only necessary to initialize using the internet with a Wi-Fi connection. Once the device has been activated, an initial calibration is automatically executed, and this enables remote diagnostics and maintenance. Similarly, the periodic device updates are carried out automatically. * Data quality control is carried out in the centralized servers using validation algorithms that compare the data collected from the adjacent AWSs, within the same geographic area, in order to identify atypical values due to faults in the device or to an inadequate installation [82]. * It does not have averaging operations, manual entry of observations, data reduction, or local data visualization. * As for the peripheral equipment, this device is powered by two AAA batteries with an approximate autonomy of two years for data collection occurring every five minutes. In order to ensure the accuracy of the timings, temporal synchronization mechanisms based on network protocols (such as NTP) are used. Although the manufacturer does not detail the implementation of a clock in real time, the network architecture guarantees that the data from each sensor are coherently integrated in the cloud, allowing precise chronologies [82; 83]. Whether the AWSs have specific devices for quality control is not known. The models compatible with WU [79] and their characteristics can be seen in Appendix A. It has been verified that there is no Netatmo station registered in the WU network in the city of Caceres. All the pieces of equipment are made of resistant materials and are made up of totally functional measuring devices that include such auxiliary elements from the factory as a radiation screen. They are also connected to the CPU. The WU network includes stations installed between 2020 and 2024.