Quantifying the Independent Influences of Land Cover and Humidity on Microscale Urban Air Temperature Variation in Hot Summer: Methods of Path Analysis and Genetic SVR

• Published in: Atmosphere 2020-12, Vol.11 (12), p.1377
• Main Authors: Shi, Weifang, Wang, Nan, Xin, Aixuan, Liu, Linglan, Hou, Jiaqi, Zhang, Yirui
• Format: Article
• Language: English
• Subjects: Air pollution; Air temperature; Analysis; Cities; genetic algorithm; Genetic analysis; Greenhouse gases; Heat; Heat waves; Heatwaves; high air temperature; High temperature; Humidity; Humidity effects; Influence; Land cover; Microclimate; Mitigation; Outdoor air quality; path analysis; Pollution control; Public health; Relative humidity; Seasonal variations; Summer; Support vector machines; support vector regression; Sustainable development; Temperature; Temperature variations; Urban air; Urban areas; Vegetation
• ISSN: 2073-4433; 2073-4433
• DOI: 10.3390/atmos11121377

Mitigating high air temperatures and heat waves is vital for decreasing air pollution and protecting public health. To improve understanding of microscale urban air temperature variation, this paper performed measurements of air temperature and relative humidity in a field of Wuhan City in the afternoon of hot summer days, and used path analysis and genetic support vector regression (SVR) to quantify the independent influences of land cover and humidity on air temperature variation. The path analysis shows that most effect of the land cover is mediated through relative humidity difference, more than four times as much as the direct effect, and that the direct effect of relative humidity difference is nearly six times that of land cover, even larger than the total effect of the land cover. The SVR simulation illustrates that land cover and relative humidity independently contribute 16.3% and 83.7%, on average, to the rise of the air temperature over the land without vegetation in the study site. An alternative strategy of increasing the humidity artificially is proposed to reduce high air temperatures in urban areas. The study would provide scientific support for the regulation of the microclimate and the mitigation of the high air temperature in urban areas.