Seasonal Variation in Air Temperature and Relative Humidity on Building Areas and in Green Spaces in Beijing, China

Abstract

The cooling and humidifying effects of urban parks are an essential component of city ecosystems in terms of regulating microclimates or mitigating urban heat islands (UHIs). Air temperature and relative humidity are two main factors of thermal environmental comfort and have a critical impact on the urban environmental quality of human settlements. We measured the 2-m height air temperature and relative humidity at the Beijing Olympic Park and a nearby building roof for more than 1 year to elucidate seasonal variations in air temperature and relative humidity, as well as to investigate the outdoor thermal comfort. The results showed that the lawn of the park could, on average, reduce the air temperature by (0.80±0.19) , and increase the relative humidity by ℃ (5.24±2.91)% relative to the values measured at the building roof during daytime. During the nighttime, the lawn of the park reduced the air temperature by (2.64±0.64) and increased the relative ℃ humidity by (10.77±5.20)%. The park was cooler and more humid than surrounding building area, especially in night period (more pronounced cooling with 1.84 ). Additionally, the lawn of the park could improve ou ℃ tdoor thermal comfort through its cooling and humidifying effects. The level of thermal comfort in the park was higher than that around the building roof for a total of 11 days annually in which it was above one or more thermal comfort levels (average reduced human comfort index of 0.92) except during the winter.

Micrometeorological measurements and biometeorological survey in different urban settings of Novi Sad (Serbia)

“…For example, the average value of RH during October in Beijing (China) in the park is about 54% in the afternoon, while at the city square, RH was lower (43%). Thus, the difference in RH between locations was about 11% during the daytime, but as the day went on, the differences became more pronounced (20%) (Kuang, 2020). A similar observation can be seen in the city of Novi Sad.…”

“…The urban park had a lower temperature compared to the city square during the whole measurement, while compared to the urban street, it had a lower value of Ta only after 2 p.m. Our results are generally in line with other intra-urban micrometeorological studies. For example, in Beijing (China) the difference in Ta between the park (vegetation) and the street (buildings) was about 1.24 o C during daytime (Kuang, 2020), while in Novi Sad the average Ta difference between these two locations was less severe (only about 0.4 o C). These differences may vary because of the measurement period, urban form or even the human activities during the day.…”

Study of Urban Heat Island Effect in Hangzhou Metropolitan Area Based on SW-TES Algorithm and Image Dichotomous Model

“…H. Du et al (2021) conducted microclimate field measurements on 35 gas storage reservoirs in Shanghai, China, and investigated the effect of urban green space on temperature through data collection and statistical analysis, eventually found that the shape of the urban green space had a significant effect on the temperature and humidity index (THI). Kuang (2020) measured air temperature and relative humidity at 2 m height on the roofs of the Beijing Olympic Park and nearby buildings for more than 1 year. The results indicate that the cooling and humidifying effects of urban parks are an important component of urban ecosystems.…”

Improving Urban Resilience through Green Infrastructure: An Integrated Approach for Connectivity Conservation in the Central City of Shenyang, China

“…erefore, it can be seen that the fragmentation of GI components caused by the rapid urbanization is also the cause for their evolution from large-scale development and centralization toward the direction of the network. e urban GI can be guided to a more resilient trajectory and made conducive for the improvement of urban resilience if the opportunity can be seized and scientifically reasonable protection measures are taken [61]. is radically changes our understanding of a larger green space being more suitable for an optimized pattern and function contributing toward the resilient development of the city.…”