Developing an optimized method for the ‘stop-and-go’ strategy in mobile measurements for characterizing outdoor thermal environments

Abstract

Outdoor thermal measurement is the most direct and accurate technique to investigate and assess urban overheating. Thanks to operational convenience and low costs, mobile measurements are regarded as more efficient than fixed measurements. However, the accuracy of mobile measurements has not been adequately studied, especially given the lack of a standardized method for “stop-and-go”. This paper aimed to develop an optimized method suitable for mobile measurements. By comparing data from mobile and fixed points, the settling time, the effective period, and the staying time of air temperature (Ta) and black globe temperature (Tg) were elucidated. Further verification and application of this optimized method was achieved. The results show that: (i) the spatial transformation caused initial differences for both Ta and Tg, which could be reduced by average settling times of 3.1 min and 4.6 min, respectively; (ii) elimination of the data in the first 5 min improved the result accuracy of Ta by 20 % and Tg by 30 %; and (iii) a staying time of 10 min could afford acceptable result accuracy. In short, through regulating the settling time and staying time, the optimized method for mobile measurements could achieve excellent result accuracy on thermal environments in complex urban spaces.