# A Portable Non-Motorized Smart IoT Weather Station Platform for Urban Thermal Comfort Studies
## 1 Introduction
Unlike the AoT (typically mounted to the lamp posts or other street furniture), wireless smart sensors used in mobile weather stations have facilitated high spatial-resolution data collection as they allow measuring atmospheric variables at locations of particular interest (such as in front of a shop, or a residential building, etc.). Since a mobile weather station consists of only one set of smart sensors to measure various atmospheric variables, they are considered cost-effective and sustainable compared to a fixed wireless sensor network with hundreds or thousands of sensor units. Among the mobile weather stations, the non-motorized (bicycle, cart, walking) weather stations can even measure the atmospheric variables in pedestrian pathways and cycleways in the city, facilitating a finer spatial scale compared to motorized (car, motorbike, bus, train, etc.) weather stations [18]. For any thermal comfort study, Air Temperature (AT), Relative Humidity (RH), Wind Speed (WS), and Mean Radiant Temperature (MRT) are the four variables that need to be measured. Among these four variables, MRT is not directly measured but is calculated using short-wave and long-wave radiation measurements obtained from pyranometers and pyrgeometers, respectively, which are positioned in six orthogonal directions (up-down, north-south, east-west) or calculated using Globe Temperature (GT) measurements. GT is an integrated temperature value of dry-bulb temperature, air movement, and net radiant heat received from the surrounding surface [19]. Therefore, in [20; 21; 22; 23] authors took advantage of pyranometers to record short-wave radiation measurements in addition to AT, RH, and WS. Whereas, in [24; 25], authors also measured both the short-wave and long-wave radiation to accurately obain the MRT using pyranometers and pyrgeometers, respectivelyHowever, this approach is less cost-efficient compared to GT as pyranometers and pyrgeometers are relatively much more expensive [26]. In [27; 28], AT and RH were only measured, whereas [29; 30; 31; 32; 33] also included WS. These studies used commercially available portable sensor devices, HOBO data loggers and sensors [27; 28; 29; 33]; Kestrel 5500 [30]; KX-5 ultrasonic weather station [31]; and ZK-YD6A and TESTO405-V1 hand-held heat-sensitive anemometers [32]. An external data logger was also used by the studies to connect and acquire data from the sensors [29]. The studies [21; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43] also measured GT along with the other three variables for calculating MRT. They used two sensor devices, as the commercially available portable sensor devices do not facilitate GT measurements: the first device to measure AT, RH, and WS, and the second device with an AT sensor customized for GT measurements. Even though some of these devices support IoT integration for real-time monitoring, the absence of sensors to measure GT makes them unfit for outdoor thermal comfort studies. Additionally, ultrasonic wind sensors for measuring wind speed and direction are expensive (\(\copy 849 to \(\copy 1393\)), though precise, compared to cup anemometers (\(\copy 30 to \(\copy 50\)). [PERSON] et al. [26] suggest a 40 mm flat grey globe thermometer for GT measurement. Authors proposed a temperature sensor inside a table tennis ball painted with RAL 7001 (flat grey) color, as it provides accurate results according to ISO 7726 (1998) [44] and the ASHRAE handbook of fundamentals. The 150 mm diameter copper globe thermometers have large time constants and are not recommended for outdoor thermal comfort studies [26]. Commercial products to measure GT include the WBGT-2010 SD heat stress meter with a 75 mm black globe [42]; TM-188 heat stress meter with a 50 mm brass black [37]; and TP3275 globe thermometer, which has a Pt100 temperature sensor inside a 150 mm black globe [39]. A a 150 mm diameter globe, a 25 mm diameter black globe calibrated to achieve the standard of a 150 mm diameter globe, and a 75 mm diameter black globe, respectively are used in [35; 40; 45]. Alternatively, [PERSON] et.al.