Abstract
Urban heat island (UHI) is one major anthropogenic modification to the Earth system that transcends its physical boundary. Using MODIS data from 2003 to 2012, we showed that the UHI effect decayed exponentially toward rural areas for majority of the 32 Chinese cities. We found an obvious urban/rural temperature “cliff”, and estimated that the footprint of UHI effect (FP, including urban area) was 2.3 and 3.9 times of urban size for the day and night, respectively, with large spatiotemporal heterogeneities. We further revealed that ignoring the FP may underestimate the UHI intensity in most cases and even alter the direction of UHI estimates for few cities. Our results provide new insights to the characteristics of UHI effect and emphasize the necessity of considering city- and time-specific FP when assessing the urbanization effects on local climate.
Highlights
Urban heat island (UHI) is one major anthropogenic modification to the Earth system that transcends its physical boundary
We examined the UHI effect in 32 major cities distributed in different climatic zones of China (Fig. 1) using Moderate Resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) products in conjunction with cloud-free Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+ ) images during the period from 2003 to 2012
The decline trends were observed more obvious in summer than winter during the day, which can be mainly attributed to much stronger UHI effect[10,11] and much more active convection together with the related circulation[24] in summer than winter during the daytime
Summary
Urban heat island (UHI) is one major anthropogenic modification to the Earth system that transcends its physical boundary. Urbanization can pose many negative impacts on Earth’s environments that transcend far from its physical boundary[5] Among these impacts, the urban heat island (UHI), referred as the phenomenon that urban areas tend to have higher temperatures than surrounding areas, has long gained considerable interest among scientists and urban planners[6,7,8,9,10,11,12]. Zhang et al.[18] might be the only study that addressed this issue at a regional level They found that the FP on average can reach up to 2.4 times of the actual urban land cover (including urban area) in the eastern North America, but they did not explore the spatiotemporal variability. The most recent global study[10] indicated that the UHI effect was mainly limited within the area twice the urban area, but it did www.nature.com/scientificreports/
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