Changes in Wind Speed under Heat Waves Enhance Urban Heat Islands in the Beijing Metropolitan Area

• Published in: Journal of applied meteorology and climatology 2016-11, Vol.55 (11), p.2369-2375
• Main Authors: Li, Dan, Sun, Ting, Liu, Maofeng, Wang, Linlin, Gao, Zhiqiu
• Format: Article
• Language: English
• Subjects: Advection; Atmospheric chemistry; Climate change; Climatology; Daytime; Dye dispersion; Energy; Energy balance; Heat; Heat islands; Heat waves; Heatwaves; Humidity; Islands; Laboratories; Mathematical analysis; Mathematical models; Metropolitan areas; Night; Night-time; Nighttime; Physics; Rural areas; Science; Studies; Surface energy; Surface energy balance; Surface properties; Temperature; Towers; Urban heat islands; Vertical profiles; Wind speed
• ISSN: 1558-8424; 1558-8432
• DOI: 10.1175/jamc-d-16-0102.1

The interaction between urban heat islands (UHIs) and heat waves (HWs) is studied using measurements collected at two towers in the Beijing, China, metropolitan area and an analytical model. Measurements show that 1) the positive interaction between UHIs and HWs not only exists at the surface but also persists to higher levels (up to ∼70 m) and 2) the urban wind speed is enhanced by HWs during daytime but reduced during nighttime as compared with its rural counterpart. A steady-state advection–diffusion model coupled to the surface energy balance equation is then employed to understand the implication of changes in wind speed on UHIs, which reveals that the observed changes in wind speed positively contribute to the interaction between UHIs and HWs in both daytime and nighttime. The vertical structure of the positive interaction between UHIs and HWs is thus likely an outcome resulting from a combination of changes in the surface energy balance and wind profile.