Field measurement of the urban pedestrian level wind turbulence

The utilization of outdoor spaces is affected by its thermal environment, and wind, which determines the convective heat loss from the human body, is one of the most influencing factors of thermal comfort. There is a lack of study of the correlation between the convective heat loss and the wind turbulence at the pedestrian height. In this study, we measured the wind speed and turbulence characteristics within the first 2-m above ground level at three city green-spaces surrounded by buildings of different heights and densities. To accurately calculate the turbulence intensity from the time-series of wind velocity data, the synoptic trend was removed, otherwise it may cause over-estimation of the 10-min average turbulence intensity by 30–60%. The present onsite wind measurements show that the average turbulence intensity ranges from 22 to 48%, and the turbulence scale is within 1.2–12.0 m. Since wind effect on convective heat transfer is mediated through its impact on the convective heat transfer coefficient, which is often obtained experimentally in a controlled environment, the onsite wind data from this study provides a reference for the design of the experimental conditions.