Venter Zander S, Chakraborty Tirthankar, Lee Xuhui
Terrestrial Ecology Section, Norwegian Institute for Nature Research-NINA, 0349 Oslo, Norway.
School of the Environment, Yale University, New Haven, CT, USA.
Sci Adv. 2021 May 26;7(22). doi: 10.1126/sciadv.abb9569. Print 2021 May.
The ubiquitous nature of satellite data has led to an explosion of studies on the surface urban heat island (SUHI). Relatively few have simultaneously used air temperature measurements to compare SUHI with the canopy UHI (CUHI), which is more relevant to public health. Using crowdsourced citizen weather stations (>50,000) and satellite data over Europe, we estimate the CUHI and SUHI intensity in 342 urban clusters during the 2019 heat wave. Satellites produce a sixfold overestimate of UHI relative to station measurements (mean SUHI 1.45°C; CUHI 0.26°C), with SUHI exceeding CUHI in 96% of cities during daytime and in 80% at night. Using empirical evidence, we confirm the control of aerodynamic roughness on UHI intensity, but find evaporative cooling to have a stronger overall impact during this time period. Our results support urban greening as an effective UHI mitigation strategy and caution against relying on satellite data for urban heat risk assessments.
卫星数据的广泛存在导致了关于地表城市热岛（SUHI）研究的激增。相对较少的研究同时使用气温测量数据来将SUHI与冠层城市热岛（CUHI）进行比较，而CUHI与公众健康的相关性更强。利用欧洲范围内众包的公民气象站（超过50000个）和卫星数据，我们估算了2019年热浪期间342个城市集群中的CUHI和SUHI强度。相对于气象站测量数据，卫星对城市热岛的高估了六倍（平均SUHI为1.45°C；CUHI为0.26°C），白天96%的城市以及夜间80%的城市中SUHI超过CUHI。通过实证证据，我们证实了空气动力学粗糙度对城市热岛强度的控制作用，但发现在这一时期蒸发冷却的总体影响更强。我们的结果支持城市绿化作为减轻城市热岛效应的有效策略，并提醒人们在城市热风险评估中不要依赖卫星数据。
